Vulnerability-Lookup

CVE-2025-8277 (GCVE-0-2025-8277)

Vulnerability from cvelistv5 – Published: 2025-09-09 11:55 – Updated: 2026-09-01 12:08

Title

Libssh: memory exhaustion via repeated key exchange in libssh

Summary

A flaw was found in libssh's handling of key exchange (KEX) processes when a client repeatedly sends incorrect KEX guesses. The library fails to free memory during these rekey operations, which can gradually exhaust system memory. This issue can lead to crashes on the client side, particularly when using libgcrypt, which impacts application stability and availability.

Severity

3.1 (Low)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2025-09-09 19:28 UTC

CWE

CWE-401 - Missing Release of Memory after Effective Lifetime

Assigner

redhat CNA under the redhat root

CNA scorecard B 82/100 over 1045 records in the last 180 days details

References

4 references

URL	Tags
https://access.redhat.com/errata/RHSA-2026:18683	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/security/cve/CVE-2025-8277	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2383888	issue-trackingx_refsource_REDHAT
https://www.libssh.org/security/advisories/CVE-20…

Impacted products

7 products

Vendor	Product	Version
		Affected: 0.6.0 , < 0.11.3 (semver)
Red Hat	Red Hat Enterprise Linux 9	Unaffected: 0:0.10.4-18.el9 , < * (rpm) cpe:/a:redhat:enterprise_linux:9::appstream cpe:/o:redhat:enterprise_linux:9::baseos
Red Hat	Red Hat Enterprise Linux 10	cpe:/o:redhat:enterprise_linux:10
Red Hat	Red Hat Enterprise Linux 6	cpe:/o:redhat:enterprise_linux:6
Red Hat	Red Hat Enterprise Linux 7	cpe:/o:redhat:enterprise_linux:7
Red Hat	Red Hat Enterprise Linux 8	cpe:/o:redhat:enterprise_linux:8
Red Hat	Red Hat OpenShift Container Platform 4	cpe:/a:redhat:openshift:4

Date Public

2025-09-09 00:00

Credits

Red Hat would like to thank Francesco Rollo for reporting this issue.

Show details on NVD website

JSON

To clipboard

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                "cpe:/a:redhat:openshift:4"
              ],
              "defaultStatus": "affected",
              "packageName": "openshift/ose-rhel-coreos-9",
              "product": "Red Hat OpenShift Container Platform 4",
              "vendor": "Red Hat"
            }
          ],
          "credits": [
            {
              "lang": "en",
              "value": "Red Hat would like to thank Francesco Rollo for reporting this issue."
            }
          ],
          "datePublic": "2025-09-09T00:00:00.000Z",
          "descriptions": [
            {
              "lang": "en",
              "value": "A flaw was found in libssh\u0027s handling of key exchange (KEX) processes when a client repeatedly sends incorrect KEX guesses. The library fails to free memory during these rekey operations, which can gradually exhaust system memory. This issue can lead to crashes on the client side, particularly when using libgcrypt, which impacts application stability and availability."
            }
          ],
          "metrics": [
            {
              "other": {
                "content": {
                  "namespace": "https://access.redhat.com/security/updates/classification/",
                  "value": "Low"
                },
                "type": "Red Hat severity rating"
              }
            },
            {
              "cvssV3_1": {
                "attackComplexity": "HIGH",
                "attackVector": "NETWORK",
                "availabilityImpact": "LOW",
                "baseScore": 3.1,
                "baseSeverity": "LOW",
                "confidentialityImpact": "NONE",
                "integrityImpact": "NONE",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L",
                "version": "3.1"
              },
              "format": "CVSS"
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-401",
                  "description": "Missing Release of Memory after Effective Lifetime",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-09-01T12:08:29.005Z",
            "orgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
            "shortName": "redhat"
          },
          "references": [
            {
              "name": "RHSA-2026:18683",
              "tags": [
                "vendor-advisory",
                "x_refsource_REDHAT"
              ],
              "url": "https://access.redhat.com/errata/RHSA-2026:18683"
            },
            {
              "tags": [
                "vdb-entry",
                "x_refsource_REDHAT"
              ],
              "url": "https://access.redhat.com/security/cve/CVE-2025-8277"
            },
            {
              "name": "RHBZ#2383888",
              "tags": [
                "issue-tracking",
                "x_refsource_REDHAT"
              ],
              "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2383888"
            },
            {
              "url": "https://www.libssh.org/security/advisories/CVE-2025-8277.txt"
            }
          ],
          "timeline": [
            {
              "lang": "en",
              "time": "2025-07-28T11:01:26.808Z",
              "value": "Reported to Red Hat."
            },
            {
              "lang": "en",
              "time": "2025-09-09T00:00:00.000Z",
              "value": "Made public."
            }
          ],
          "title": "Libssh: memory exhaustion via repeated key exchange in libssh",
          "workarounds": [
            {
              "lang": "en",
              "value": "Mitigation for this issue is either not available or the currently available options don\u0027t meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. It is strongly advised to apply updated libssh packages once available to prevent memory exhaustion risks on client systems."
            }
          ],
          "x_generator": {
            "engine": "cvelib 1.8.0"
          },
          "x_redhatCweChain": "CWE-401: Missing Release of Memory after Effective Lifetime"
        }
      },
      "cveMetadata": {
        "assignerOrgId": "53f830b8-0a3f-465b-8143-3b8a9948e749",
        "assignerShortName": "redhat",
        "cveId": "CVE-2025-8277",
        "datePublished": "2025-09-09T11:55:39.036Z",
        "dateReserved": "2025-07-28T11:02:27.938Z",
        "dateUpdated": "2026-09-01T12:08:29.005Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

SUSE-SU-2026:21396-1

Vulnerability from csaf_suse - Published: 2026-04-30 09:40 - Updated: 2026-10-15 17:06

Summary

Security update for libssh

Severity

Moderate

Scope

7 vulnerabilities in this advisory, including CVE-2025-8277.

CVE-2025-8277

3.1 (Low)


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

Recommended: 5 products

Open the full advisory

SUSE-SU-2026:21428-1

Vulnerability from csaf_suse - Published: 2026-04-30 09:40 - Updated: 2026-09-16 19:45

Summary

Security update for libssh

Severity

Moderate

Scope

7 vulnerabilities in this advisory, including CVE-2025-8277.

CVE-2025-8277

3.1 (Low)


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

Recommended: 18 products

Open the full advisory

UBUNTU-CVE-2025-8277 (CVE-2025-8277)

Vulnerability from osv_ubuntu – Published: 2025-09-09 12:15 – Updated: 2026-04-22 07:53 – Source website

Details

Severity

3.1 (Low)


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

N/A (UNKNOWN)

low

References

URL

Type

	https://ubuntu.com/security/CVE-2025-8277	REPORT
	https://www.cve.org/CVERecord?id=CVE-2025-8277	REPORT
	https://www.libssh.org/security/advisories/CVE-20…	REPORT
	https://access.redhat.com/security/cve/CVE-2025-8277	REPORT
	https://ubuntu.com/security/notices/USN-8051-1	ADVISORY
	https://ubuntu.com/security/notices/USN-8051-2	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libssh-4",
            "binary_version": "0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6"
          },
          {
            "binary_name": "libssh-gcrypt-4",
            "binary_version": "0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6"
          }
        ],
        "priority_reason": "libssh developers consider this to be a low severity issue"
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:18.04:LTS",
        "name": "libssh",
        "purl": "pkg:deb/ubuntu/libssh@0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6?arch=source\u0026distro=esm-infra/bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.7.5-1",
        "0.8.0~20170825.94fa1e38-1",
        "0.8.0~20170825.94fa1e38-1build1",
        "0.8.0~20170825.94fa1e38-1ubuntu0.1",
        "0.8.0~20170825.94fa1e38-1ubuntu0.2",
        "0.8.0~20170825.94fa1e38-1ubuntu0.5",
        "0.8.0~20170825.94fa1e38-1ubuntu0.6",
        "0.8.0~20170825.94fa1e38-1ubuntu0.7",
        "0.8.0~20170825.94fa1e38-1ubuntu0.7+esm3",
        "0.8.0~20170825.94fa1e38-1ubuntu0.7+esm4",
        "0.8.0~20170825.94fa1e38-1ubuntu0.7+esm5"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro",
        "binaries": [
          {
            "binary_name": "libssh-4",
            "binary_version": "0.9.3-2ubuntu2.5+esm3"
          },
          {
            "binary_name": "libssh-gcrypt-4",
            "binary_version": "0.9.3-2ubuntu2.5+esm3"
          }
        ],
        "priority_reason": "libssh developers consider this to be a low severity issue"
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "libssh",
        "purl": "pkg:deb/ubuntu/libssh@0.9.3-2ubuntu2.5+esm3?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.3-2ubuntu2.5+esm3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.9.0-1ubuntu1",
        "0.9.0-1ubuntu4",
        "0.9.0-1ubuntu5",
        "0.9.3-2ubuntu1",
        "0.9.3-2ubuntu2",
        "0.9.3-2ubuntu2.1",
        "0.9.3-2ubuntu2.2",
        "0.9.3-2ubuntu2.3",
        "0.9.3-2ubuntu2.4",
        "0.9.3-2ubuntu2.5",
        "0.9.3-2ubuntu2.5+esm1",
        "0.9.3-2ubuntu2.5+esm2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh-4",
            "binary_version": "0.9.6-2ubuntu0.22.04.6"
          },
          {
            "binary_name": "libssh-gcrypt-4",
            "binary_version": "0.9.6-2ubuntu0.22.04.6"
          }
        ],
        "priority_reason": "libssh developers consider this to be a low severity issue"
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "libssh",
        "purl": "pkg:deb/ubuntu/libssh@0.9.6-2ubuntu0.22.04.6?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.9.6-2ubuntu0.22.04.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.9.6-1",
        "0.9.6-1build1",
        "0.9.6-2",
        "0.9.6-2build1",
        "0.9.6-2ubuntu0.22.04.1",
        "0.9.6-2ubuntu0.22.04.2",
        "0.9.6-2ubuntu0.22.04.3",
        "0.9.6-2ubuntu0.22.04.4",
        "0.9.6-2ubuntu0.22.04.5"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh-4",
            "binary_version": "0.10.6-2ubuntu0.3"
          },
          {
            "binary_name": "libssh-gcrypt-4",
            "binary_version": "0.10.6-2ubuntu0.3"
          }
        ],
        "priority_reason": "libssh developers consider this to be a low severity issue"
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "libssh",
        "purl": "pkg:deb/ubuntu/libssh@0.10.6-2ubuntu0.3?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.10.6-2ubuntu0.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.10.5-3ubuntu1",
        "0.10.5-3ubuntu2",
        "0.10.6-2",
        "0.10.6-2build1",
        "0.10.6-2build2",
        "0.10.6-2ubuntu0.1",
        "0.10.6-2ubuntu0.2"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "libssh-4",
            "binary_version": "0.11.2-1ubuntu0.2"
          }
        ],
        "priority_reason": "libssh developers consider this to be a low severity issue"
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "libssh",
        "purl": "pkg:deb/ubuntu/libssh@0.11.2-1ubuntu0.2?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.11.2-1ubuntu0.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.11.1-1",
        "0.11.1-2",
        "0.11.2-1",
        "0.11.2-1build1",
        "0.11.2-1ubuntu0.1"
      ]
    }
  ],
  "aliases": [],
  "details": "A flaw was found in libssh\u0027s handling of key exchange (KEX) processes when a client repeatedly sends incorrect KEX guesses. The library fails to free memory during these rekey operations, which can gradually exhaust system memory. This issue can lead to crashes on the client side, particularly when using libgcrypt, which impacts application stability and availability.",
  "id": "UBUNTU-CVE-2025-8277",
  "modified": "2026-04-22T07:53:19Z",
  "published": "2025-09-09T12:15:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2025-8277"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-8277"
    },
    {
      "type": "REPORT",
      "url": "https://www.libssh.org/security/advisories/CVE-2025-8277.txt"
    },
    {
      "type": "REPORT",
      "url": "https://access.redhat.com/security/cve/CVE-2025-8277"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8051-1"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8051-2"
    }
  ],
  "related": [
    "USN-8051-1",
    "USN-8051-2"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    },
    {
      "score": "low",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2025-8277"
  ]
}

WID-SEC-W-2025-2002

Vulnerability from csaf_certbund - Published: 2025-09-09 22:00 - Updated: 2026-05-28 22:00

Summary

libssh: Schwachstelle ermöglicht Denial of Service

Severity

Niedrig

Scope

1 vulnerability in this advisory, including CVE-2025-8277.

CVE-2025-8277

Known affected: 9 products

Open the full advisory

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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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.

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CVE-2025-8277 (GCVE-0-2025-8277)

SUSE-SU-2026:21396-1

SUSE-SU-2026:21428-1

UBUNTU-CVE-2025-8277 (CVE-2025-8277)

WID-SEC-W-2025-2002

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