Vulnerability-Lookup

CVE-2026-34988 (GCVE-0-2026-34988)

Vulnerability from cvelistv5 – Published: 2026-04-09 18:52 – Updated: 2026-04-09 19:31

Title

Wasmtime leaks data between pooling allocator instances

Summary

Wasmtime is a runtime for WebAssembly. From 28.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime's implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon. The pooling allocator must be in use, Config::memory_guard_size configuration option must be 0, Config::memory_reservation configuration must be less than 4GiB, and pooling allocator must be configured with max_memory_size the same as the memory_reservation value in order to exploit this vulnerability. If all of these conditions are applicable then when a linear memory is reused the VM permissions of the previous iteration are not reset. This means that the compiled code, which is assuming out-of-bounds loads will segfault, will not actually segfault and can read the previous contents of linear memory if it was previously mapped. This represents a data leakage vulnerability between guest WebAssembly instances which breaks WebAssembly's semantics and additionally breaks the sandbox that Wasmtime provides. Wasmtime is not vulnerable to this issue with its default settings, nor with the default settings of the pooling allocator, but embeddings are still allowed to configure these values to cause this vulnerability. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.

Severity

2.3 (Low)


                        
                          CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-09 19:30 UTC

CWE

CWE-119 - Improper Restriction of Operations within the Bounds of a Memory Buffer

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 8035 records in the last 180 days details

References

1 reference

URL	Tags
https://github.com/bytecodealliance/wasmtime/secu…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version	CPE status
bytecodealliance	wasmtime	Affected: >= 28.0.0, < 36.0.7 Affected: >= 37.0.0, < 42.0.2 Affected: >= 43.0.0, < 44.0.1	guessed

Show details on NVD website

JSON

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FKIE_CVE-2026-34988

Vulnerability from fkie_nvd - Published: 2026-04-09 19:16 - Updated: 2026-10-26 22:10

Severity

6.3 (Medium) - CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6wgr-89rj-399p	Mitigation, Vendor Advisory

Impacted products

Vendor	Product	Version
bytecodealliance	wasmtime	*
bytecodealliance	wasmtime	*
bytecodealliance	wasmtime	43.0.0

JSON

To clipboard

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              "status": "affected",
              "version": "\u003e= 28.0.0, \u003c 36.0.7"
            },
            {
              "status": "affected",
              "version": "\u003e= 37.0.0, \u003c 42.0.2"
            },
            {
              "status": "affected",
              "version": "\u003e= 43.0.0, \u003c 44.0.1"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*",
              "matchCriteriaId": "3D8A5C5B-5869-46AA-8442-1B5B3B566C80",
              "versionEndExcluding": "36.0.7",
              "versionStartIncluding": "28.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:rust:*:*",
              "matchCriteriaId": "1D7B70EB-93E3-4732-AB70-E6A531178941",
              "versionEndExcluding": "42.0.2",
              "versionStartIncluding": "37.0.0",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:a:bytecodealliance:wasmtime:43.0.0:*:*:*:*:rust:*:*",
              "matchCriteriaId": "9AD0150A-FE79-4EA6-995B-8CAFC7F246B5",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Wasmtime is a runtime for WebAssembly. From 28.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime\u0027s implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon. The pooling allocator must be in use, Config::memory_guard_size configuration option must be 0, Config::memory_reservation configuration must be less than 4GiB, and pooling allocator must be configured with max_memory_size the same as the memory_reservation value in order to exploit this vulnerability. If all of these conditions are applicable then when a linear memory is reused the VM permissions of the previous iteration are not reset. This means that the compiled code, which is assuming out-of-bounds loads will segfault, will not actually segfault and can read the previous contents of linear memory if it was previously mapped. This represents a data leakage vulnerability between guest WebAssembly instances which breaks WebAssembly\u0027s semantics and additionally breaks the sandbox that Wasmtime provides. Wasmtime is not vulnerable to this issue with its default settings, nor with the default settings of the pooling allocator, but embeddings are still allowed to configure these values to cause this vulnerability. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1."
    },
    {
      "lang": "es",
      "value": "Wasmtime es un runtime para WebAssembly. Desde la versi\u00f3n 28.0.0 hasta antes de las versiones 36.0.7, 42.0.2 y 43.0.1, la implementaci\u00f3n de Wasmtime de su asignador de pooling contiene un error donde en ciertas configuraciones el contenido de la memoria lineal puede filtrarse de una instancia a la siguiente. La implementaci\u00f3n del restablecimiento de los permisos de memoria virtual para la memoria lineal utiliz\u00f3 el predicado incorrecto para determinar si el restablecimiento era necesario, mientras que el proceso de compilaci\u00f3n utilizaba un predicado diferente. Esta divergencia signific\u00f3 que el asignador de pooling dedujo incorrectamente en tiempo de ejecuci\u00f3n que el restablecimiento de los permisos de memoria virtual no era necesario, mientras que en tiempo de compilaci\u00f3n se determin\u00f3 que se pod\u00eda confiar en la memoria virtual. El asignador de pooling debe estar en uso, la opci\u00f3n de configuraci\u00f3n Config::memory_guard_size debe ser 0, la configuraci\u00f3n Config::memory_reservation debe ser inferior a 4GiB, y el asignador de pooling debe configurarse con max_memory_size igual al valor de memory_reservation para poder explotar esta vulnerabilidad. Si todas estas condiciones son aplicables, entonces cuando una memoria lineal es reutilizada los permisos de la VM de la iteraci\u00f3n anterior no se restablecen. Esto significa que el c\u00f3digo compilado, que asume que las cargas fuera de l\u00edmites provocar\u00e1n un segfault, en realidad no provocar\u00e1 un segfault y podr\u00e1 leer el contenido anterior de la memoria lineal si esta fue mapeada previamente. Esto representa una vulnerabilidad de fuga de datos entre instancias de WebAssembly invitadas, lo que rompe la sem\u00e1ntica de WebAssembly y adicionalmente rompe el sandbox que Wasmtime proporciona. Wasmtime no es vulnerable a este problema con su configuraci\u00f3n predeterminada, ni con la configuraci\u00f3n predeterminada del asignador de pooling, pero las incrustaciones a\u00fan pueden configurar estos valores para causar esta vulnerabilidad. Esta vulnerabilidad se corrige en las versiones 36.0.7, 42.0.2 y 43.0.1."
    }
  ],
  "id": "CVE-2026-34988",
  "lastModified": "2026-10-26T22:10:00.163",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "NETWORK",
          "availabilityImpact": "NONE",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 4.0,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ],
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 2.3,
          "baseSeverity": "LOW",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "LOW",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "LOW",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-34988",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-04-09T19:30:55.518033Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-04-09T19:16:25.160",
  "references": [
    {
      "source": "security-advisories@github.com",
      "tags": [
        "Mitigation",
        "Vendor Advisory"
      ],
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6wgr-89rj-399p"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-119"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-6WGR-89RJ-399P

Vulnerability from github – Published: 2026-04-09 20:23 – Updated: 2026-04-10 14:40

Summary

Wasmtime has data leakage between pooling allocator instances

Details

Impact

Wasmtime's implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon.

Exposing this bug requires specific configuration values to be used. If any of these configurations are not applicable then this bug does not happen:

The pooling allocator must be in use.
The Config::memory_guard_size configuration option must be 0.
The Config::memory_reservation configuration must be less than 4GiB.
The pooling allocator must be configured with max_memory_size the same as the memory_reservation value.

If all of these conditions are applicable then when a linear memory is reused the VM permissions of the previous iteration are not reset. This means that the compiled code, which is assuming out-of-bounds loads will segfault, will not actually segfault and can read the previous contents of linear memory if it was previously mapped.

This represents a data leakage vulnerability between guest WebAssembly instances which breaks WebAssembly's semantics and additionally breaks the sandbox that Wasmtime provides. Wasmtime is not vulnerable to this issue with its default settings, nor with the default settings of the pooling allocator, but embeddings are still allowed to configure these values to cause this vulnerability.

Patches

Wasmtime 36.0.7, 42.0.2, and 43.0.1 have been issued to fix this bug. Users are recommended to update to these patched versions of Wasmtime.

Workarounds

All four conditions above must be met to be vulnerable to this bug, and users can work around this bug by adjusting any of the above conditions. For example it is strongly recommended that guard pages are configured for linear memories which would make this bug not applicable.

Severity

2.3 (Low)


                  
                    CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "28.0.0"
            },
            {
              "fixed": "36.0.7"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "37.0.0"
            },
            {
              "fixed": "42.0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "43.0.0"
            },
            {
              "fixed": "43.0.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "43.0.0"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34988"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-119"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-09T20:23:58Z",
    "nvd_published_at": "2026-04-09T19:16:25Z",
    "severity": "LOW"
  },
  "details": "### Impact\n\nWasmtime\u0027s implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon.\n\nExposing this bug requires specific configuration values to be used. If any of these configurations are not applicable then this bug does not happen:\n\n* The pooling allocator must be in use.\n* The `Config::memory_guard_size` configuration option must be 0.\n* The `Config::memory_reservation` configuration must be less than 4GiB.\n* The pooling allocator must be configured with `max_memory_size` the same as the `memory_reservation` value.\n\nIf all of these conditions are applicable then when a linear memory is reused the VM permissions of the previous iteration are not reset. This means that the compiled code, which is assuming out-of-bounds loads will segfault, will not actually segfault and can read the previous contents of linear memory if it was previously mapped.\n\nThis represents a data leakage vulnerability between guest WebAssembly instances which breaks WebAssembly\u0027s semantics and additionally breaks the sandbox that Wasmtime provides. Wasmtime is not vulnerable to this issue with its default settings, nor with the default settings of the pooling allocator, but embeddings are still allowed to configure these values to cause this vulnerability.\n\n### Patches\n\nWasmtime 36.0.7, 42.0.2, and 43.0.1 have been issued to fix this bug. Users are recommended to update to these patched versions of Wasmtime.\n\n### Workarounds\n\nAll four conditions above must be met to be vulnerable to this bug, and users can work around this bug by adjusting any of the above conditions. For example it is strongly recommended that guard pages are configured for linear memories which would make this bug not applicable.",
  "id": "GHSA-6wgr-89rj-399p",
  "modified": "2026-04-10T14:40:06Z",
  "published": "2026-04-09T20:23:58Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6wgr-89rj-399p"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34988"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/bytecodealliance/wasmtime"
    },
    {
      "type": "WEB",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0088.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Wasmtime has data leakage between pooling allocator instances"
}

OPENSUSE-SU-2026:10715-1

Vulnerability from csaf_opensuse - Published: 2026-05-06 00:00 - Updated: 2026-09-29 17:30

Summary

libtree-sitter0_26-0.26.8-2.1 on GA media

Severity

Moderate

Scope

4 vulnerabilities in this advisory, including CVE-2026-34988.

CVE-2026-34988

6.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Recommended: 16 products

Open the full advisory

OPENSUSE-SU-2026:20749-1

Vulnerability from csaf_opensuse - Published: 2026-05-14 08:07 - Updated: 2026-09-29 17:31

Summary

Security update for tree-sitter

Severity

Important

Scope

10 vulnerabilities in this advisory, including CVE-2026-34988.

CVE-2026-34988

6.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Recommended: 13 products

Open the full advisory

RUSTSEC-2026-0088 (CVE-2026-34988)

Vulnerability from osv_rustsec – Published: 2026-04-09 12:00 – Updated: 2026-10-12 17:47 – Source website

Summary

Data leakage between pooling allocator instances

Details

This is an entry in the RustSec database for the Wasmtime security advisory located at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6wgr-89rj-399p For more information see the GitHub-hosted security advisory.

Severity

2.3 (Low)


                    
                      CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N

References

URL

Type

	https://crates.io/crates/wasmtime	PACKAGE
	https://rustsec.org/advisories/RUSTSEC-2026-0088.html	ADVISORY
	https://github.com/bytecodealliance/wasmtime/pull/13008	WEB

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "categories": [],
        "cvss": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N",
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "wasmtime",
        "purl": "pkg:cargo/wasmtime"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "36.0.7"
            },
            {
              "introduced": "37.0.0"
            },
            {
              "fixed": "42.0.2"
            },
            {
              "introduced": "43.0.0"
            },
            {
              "fixed": "43.0.1"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2026-34988",
    "GHSA-6wgr-89rj-399p"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "This is an entry in the RustSec database for the Wasmtime security advisory\nlocated at\nhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6wgr-89rj-399p\nFor more information see the GitHub-hosted security advisory.",
  "id": "RUSTSEC-2026-0088",
  "modified": "2026-10-12T17:47:59Z",
  "published": "2026-04-09T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/wasmtime"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2026-0088.html"
    },
    {
      "type": "WEB",
      "url": "https://github.com/bytecodealliance/wasmtime/pull/13008"
    }
  ],
  "related": [],
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Data leakage between pooling allocator instances"
}

SUSE-SU-2026:21789-1

Vulnerability from csaf_suse - Published: 2026-05-14 08:09 - Updated: 2026-09-29 17:26

Summary

Security update for tree-sitter

Severity

Important

Scope

10 vulnerabilities in this advisory, including CVE-2026-34988.

CVE-2026-34988

6.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Recommended: 18 products

Open the full advisory

UBUNTU-CVE-2026-34988 (CVE-2026-34988)

Vulnerability from osv_ubuntu – Published: 2026-04-09 19:16 – Updated: 2026-10-17 09:40 – Source website

Details

Severity

2.3 (Low)


                    
                      CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N

6.3 (Medium)


                    
                      CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-34988	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-34988	REPORT
	https://github.com/bytecodealliance/wasmtime/secu…	REPORT

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librust-cranelift-dev",
            "binary_version": "0.103.0+16.0.0+dfsg-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "rust-wasmtime",
        "purl": "pkg:deb/ubuntu/rust-wasmtime@16.0.0+dfsg-3?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "10.0.1+dfsg-7",
        "15.0.1+dfsg-4",
        "16.0.0+dfsg-2",
        "16.0.0+dfsg-3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librust-cranelift-dev",
            "binary_version": "0.113.1+26.0.1+dfsg-3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "rust-wasmtime",
        "purl": "pkg:deb/ubuntu/rust-wasmtime@26.0.1+dfsg-3?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "26.0.1+dfsg-3"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librust-cranelift-dev",
            "binary_version": "0.123.13+36.0.13+dfsg-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.10",
        "name": "rust-wasmtime",
        "purl": "pkg:deb/ubuntu/rust-wasmtime@36.0.13+dfsg-1?arch=source\u0026distro=stonking"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "36.0.5+dfsg-1",
        "36.0.13+dfsg-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "librust-cranelift-dev",
            "binary_version": "0.123.5+36.0.5+dfsg-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "rust-wasmtime",
        "purl": "pkg:deb/ubuntu/rust-wasmtime@36.0.5+dfsg-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "26.0.1+dfsg-3",
        "26.0.1+dfsg-4",
        "28.0.1+dfsg-3",
        "29.0.1+dfsg-5",
        "36.0.5+dfsg-1"
      ]
    }
  ],
  "aliases": [],
  "details": "Wasmtime is a runtime for WebAssembly. From 28.0.0 to before 36.0.7, 42.0.2, and 43.0.1, Wasmtime\u0027s implementation of its pooling allocator contains a bug where in certain configurations the contents of linear memory can be leaked from one instance to the next. The implementation of resetting the virtual memory permissions for linear memory used the wrong predicate to determine if resetting was necessary, where the compilation process used a different predicate. This divergence meant that the pooling allocator incorrectly deduced at runtime that resetting virtual memory permissions was not necessary while compile-time determine that virtual memory could be relied upon. The pooling allocator must be in use, Config::memory_guard_size configuration option must be 0, Config::memory_reservation configuration must be less than 4GiB, and pooling allocator must be configured with max_memory_size the same as the memory_reservation value in order to exploit this vulnerability. If all of these conditions are applicable then when a linear memory is reused the VM permissions of the previous iteration are not reset. This means that the compiled code, which is assuming out-of-bounds loads will segfault, will not actually segfault and can read the previous contents of linear memory if it was previously mapped. This represents a data leakage vulnerability between guest WebAssembly instances which breaks WebAssembly\u0027s semantics and additionally breaks the sandbox that Wasmtime provides. Wasmtime is not vulnerable to this issue with its default settings, nor with the default settings of the pooling allocator, but embeddings are still allowed to configure these values to cause this vulnerability. This vulnerability is fixed in 36.0.7, 42.0.2, and 43.0.1.",
  "id": "UBUNTU-CVE-2026-34988",
  "modified": "2026-10-17T09:40:53Z",
  "published": "2026-04-09T19:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-34988"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-34988"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-6wgr-89rj-399p"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:L/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-34988"
  ]
}

Sightings

Author	Source	Type	Date	Other

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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

CVE-2026-34988 (GCVE-0-2026-34988)

FKIE_CVE-2026-34988

GHSA-6WGR-89RJ-399P

Impact

Patches

Workarounds

OPENSUSE-SU-2026:10715-1

OPENSUSE-SU-2026:20749-1

RUSTSEC-2026-0088 (CVE-2026-34988)

SUSE-SU-2026:21789-1

UBUNTU-CVE-2026-34988 (CVE-2026-34988)

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