CVE-2026-121751 (GCVE-0-2026-121751)

Vulnerability from cvelistv5 – Published: 2026-11-04 21:26 – Updated: 2026-11-04 21:26
VLAI
Title
nvm evaluates a malicious mirror's index.tab version strings as shell arithmetic via stored LTS aliases
Summary
Node Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.39.6 through 0.40.8, `nvm ls-remote` (and other commands that refresh remote LTS aliases) store the version column of the mirror's `index.tab` in `$NVM_DIR/alias/lts/` without validating it, and `nvm_normalize_lts` later evaluates any suffix of an `lts/-N` value inside shell arithmetic `$((N+1))`. Under bash and zsh, arithmetic evaluation expands command substitutions in array subscripts, so a stored value such as `lts/-10*path[$(cmd)1]` runs `cmd` as the user when the alias is later resolved by purely local commands (`nvm ls`, `nvm alias`, `nvm use --lts`, `nvm which lts/`), and in every new shell when the `default` alias is `lts/*`. Exploitation requires the victim to use a hostile mirror -- via a compromised mirror or CDN, a network man-in-the-middle of an `http://` mirror, or a maliciously configured `NVM_NODEJS_ORG_MIRROR` -- and to run an affected command. The same sink is also reachable from a project `.nvmrc`, which is treated as hardening. dash is not affected. Version 0.41.0 only passes an all-digit `lts/-N` offset to arithmetic and drops `index.tab` rows whose version is not a valid version string.
Severity
2.1 (Low)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
3.1 (Low)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
CWE
  • CWE-78 - Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
  • CWE-20 - Improper Input Validation
Assigner
harborist CNA under the redhat root
CNA scorecard B 86/100 over 22 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
nvm-sh nvm Affected: 0.39.6 , < 0.41.0 (semver)
guessed Create a notification for this product.
Credits
Anthropic's OSS Scanner, as vulnerabilities ANT-2026-0GXXE91V and ANT-2026-31ZIEY85 Adel Assakaf (https://github.com/assakafpix) Jordan Harband (https://github.com/ljharb)
Show details on NVD website
To clipboard 

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "nvm",
          "repo": "https://github.com/nvm-sh/nvm",
          "vendor": "nvm-sh",
          "versions": [
            {
              "lessThan": "0.41.0",
              "status": "affected",
              "version": "0.39.6",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Anthropic\u0027s OSS Scanner, as vulnerabilities ANT-2026-0GXXE91V and ANT-2026-31ZIEY85"
        },
        {
          "lang": "en",
          "type": "finder",
          "value": "Adel Assakaf (https://github.com/assakafpix)"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Jordan Harband (https://github.com/ljharb)"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
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              "value": "\u003cp\u003eNode Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.39.6 through 0.40.8, `nvm ls-remote` (and other commands that refresh remote LTS aliases) store the version column of the mirror\u0027s `index.tab` in `$NVM_DIR/alias/lts/` without validating it, and `nvm_normalize_lts` later evaluates any suffix of an `lts/-N` value inside shell arithmetic `$((N+1))`. Under bash and zsh, arithmetic evaluation expands command substitutions in array subscripts, so a stored value such as `lts/-10*path[$(cmd)1]` runs `cmd` as the user when the alias is later resolved by purely local commands (`nvm ls`, `nvm alias`, `nvm use --lts`, `nvm which lts/`), and in every new shell when the `default` alias is `lts/*`. Exploitation requires the victim to use a hostile mirror -- via a compromised mirror or CDN, a network man-in-the-middle of an `http://` mirror, or a maliciously configured `NVM_NODEJS_ORG_MIRROR` -- and to run an affected command. The same sink is also reachable from a project `.nvmrc`, which is treated as hardening. dash is not affected. Version 0.41.0 only passes an all-digit `lts/-N` offset to arithmetic and drops `index.tab` rows whose version is not a valid version string.\u003c/p\u003e"
            }
          ],
          "value": "Node Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.39.6 through 0.40.8, `nvm ls-remote` (and other commands that refresh remote LTS aliases) store the version column of the mirror\u0027s `index.tab` in `$NVM_DIR/alias/lts/` without validating it, and `nvm_normalize_lts` later evaluates any suffix of an `lts/-N` value inside shell arithmetic `$((N+1))`. Under bash and zsh, arithmetic evaluation expands command substitutions in array subscripts, so a stored value such as `lts/-10*path[$(cmd)1]` runs `cmd` as the user when the alias is later resolved by purely local commands (`nvm ls`, `nvm alias`, `nvm use --lts`, `nvm which lts/`), and in every new shell when the `default` alias is `lts/*`. Exploitation requires the victim to use a hostile mirror -- via a compromised mirror or CDN, a network man-in-the-middle of an `http://` mirror, or a maliciously configured `NVM_NODEJS_ORG_MIRROR` -- and to run an affected command. The same sink is also reachable from a project `.nvmrc`, which is treated as hardening. dash is not affected. Version 0.41.0 only passes an all-digit `lts/-N` offset to arithmetic and drops `index.tab` rows whose version is not a valid version string."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.1,
            "baseSeverity": "LOW",
            "exploitMaturity": "NOT_DEFINED",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "ACTIVE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
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            "confidentialityImpact": "NONE",
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            "userInteraction": "REQUIRED",
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            "version": "3.1"
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          "descriptions": [
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              "cweId": "CWE-78",
              "description": "CWE-78 Improper Neutralization of Special Elements used in an OS Command (\u0027OS Command Injection\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
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              "description": "CWE-20 Improper Input Validation",
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              "type": "CWE"
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          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-04T21:26:57.967Z",
        "orgId": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
        "shortName": "harborist"
      },
      "references": [
        {
          "name": "GHSA-7prg-rw9c-82h7",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://github.com/nvm-sh/nvm/security/advisories/GHSA-7prg-rw9c-82h7"
        },
        {
          "name": "Fix commit aa0572b7",
          "tags": [
            "patch"
          ],
          "url": "https://github.com/nvm-sh/nvm/commit/aa0572b7c48b2652a9f86276bbbf3840939981af"
        }
      ],
      "solutions": [
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          "lang": "en",
          "supportingMedia": [
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              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eUpgrade to nvm 0.41.0 or later, which only lets an all-digit `lts/-N` offset reach shell arithmetic and drops mirror rows with invalid version strings. (Only needed if using a non-default mirror whose metadata contents you do not trust, or running nvm in untrusted project directories.)\u003c/p\u003e"
            }
          ],
          "value": "Upgrade to nvm 0.41.0 or later, which only lets an all-digit `lts/-N` offset reach shell arithmetic and drops mirror rows with invalid version strings. (Only needed if using a non-default mirror whose metadata contents you do not trust, or running nvm in untrusted project directories.)"
        }
      ],
      "source": {
        "advisory": "GHSA-7prg-rw9c-82h7",
        "discovery": "EXTERNAL"
      },
      "title": "nvm evaluates a malicious mirror\u0027s index.tab version strings as shell arithmetic via stored LTS aliases",
      "workarounds": [
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          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eUntil upgrading, only run `nvm ls-remote` and LTS-refreshing commands against trusted mirrors over TLS, ensure `NVM_NODEJS_ORG_MIRROR` points only at a trusted endpoint, and do not run nvm in untrusted project directories.\u003c/p\u003e"
            }
          ],
          "value": "Until upgrading, only run `nvm ls-remote` and LTS-refreshing commands against trusted mirrors over TLS, ensure `NVM_NODEJS_ORG_MIRROR` points only at a trusted endpoint, and do not run nvm in untrusted project directories."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
    "assignerShortName": "harborist",
    "cveId": "CVE-2026-121751",
    "datePublished": "2026-11-04T21:26:57.967Z",
    "dateReserved": "2026-11-03T23:39:04.553Z",
    "dateUpdated": "2026-11-04T21:26:57.967Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
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      "date": "2026-11-05",
      "epss": "0.00232",
      "percentile": "0.14134"
    },
    "nvd": {
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            "affectedData": [
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                "defaultStatus": "unaffected",
                "product": "nvm",
                "repo": "https://github.com/nvm-sh/nvm",
                "vendor": "nvm-sh",
                "versions": [
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                    "status": "affected",
                    "version": "0.39.6",
                    "versionType": "semver"
                  }
                ]
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            ],
            "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158"
          }
        ],
        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "Node Version Manager (nvm) is a POSIX-compliant shell function for managing multiple node.js versions. In versions 0.39.6 through 0.40.8, `nvm ls-remote` (and other commands that refresh remote LTS aliases) store the version column of the mirror\u0027s `index.tab` in `$NVM_DIR/alias/lts/` without validating it, and `nvm_normalize_lts` later evaluates any suffix of an `lts/-N` value inside shell arithmetic `$((N+1))`. Under bash and zsh, arithmetic evaluation expands command substitutions in array subscripts, so a stored value such as `lts/-10*path[$(cmd)1]` runs `cmd` as the user when the alias is later resolved by purely local commands (`nvm ls`, `nvm alias`, `nvm use --lts`, `nvm which lts/`), and in every new shell when the `default` alias is `lts/*`. Exploitation requires the victim to use a hostile mirror -- via a compromised mirror or CDN, a network man-in-the-middle of an `http://` mirror, or a maliciously configured `NVM_NODEJS_ORG_MIRROR` -- and to run an affected command. The same sink is also reachable from a project `.nvmrc`, which is treated as hardening. dash is not affected. Version 0.41.0 only passes an all-digit `lts/-N` offset to arithmetic and drops `index.tab` rows whose version is not a valid version string."
          }
        ],
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        "lastModified": "2026-11-04T22:17:55.060",
        "metrics": {
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                "attackComplexity": "HIGH",
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                "baseSeverity": "LOW",
                "confidentialityImpact": "NONE",
                "integrityImpact": "LOW",
                "privilegesRequired": "NONE",
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                "userInteraction": "REQUIRED",
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                "attackRequirements": "PRESENT",
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                "availabilityRequirement": "NOT_DEFINED",
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                "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": "NONE",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "ACTIVE",
                "valueDensity": "NOT_DEFINED",
                "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/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": "NONE",
                "vulnIntegrityImpact": "LOW",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
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              "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
              "type": "Secondary"
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        "references": [
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            "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
            "url": "https://github.com/nvm-sh/nvm/commit/aa0572b7c48b2652a9f86276bbbf3840939981af"
          },
          {
            "source": "7ffcee3d-2c14-4c3e-b844-86c6a321a158",
            "url": "https://github.com/nvm-sh/nvm/security/advisories/GHSA-7prg-rw9c-82h7"
          }
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        "vulnStatus": "Received",
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                "value": "CWE-20"
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  }
}



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