CVE-2026-53585 (GCVE-0-2026-53585)

Vulnerability from cvelistv5 – Published: 2026-08-20 18:37 – Updated: 2026-08-20 18:37
VLAI
Title
libgit2: Unbounded Memory Allocation via Delta Object Result-Size Header
Summary
libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, git_delta_apply in src/libgit2/delta.c trusts the attacker-controlled res_sz value parsed by hdr_sz from a delta object header and passes that amount to git__malloc before validating delta instructions. Malicious pack data supplied through git_clone, git_fetch, git_remote_fetch, git_indexer_append, or a local attacker-supplied repository can use a very small multi-level OFS_DELTA chain to retain extremely large allocations and exhaust memory. This issue is fixed in versions 1.8.6 and 1.9.5.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version CPE status
libgit2 libgit2 Affected: < 1.8.6
Affected: >= 1.9.0, < 1.9.5
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "libgit2",
          "vendor": "libgit2",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.8.6"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.9.0, \u003c 1.9.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, git_delta_apply in src/libgit2/delta.c trusts the attacker-controlled res_sz value parsed by hdr_sz from a delta object header and passes that amount to git__malloc before validating delta instructions. Malicious pack data supplied through git_clone, git_fetch, git_remote_fetch, git_indexer_append, or a local attacker-supplied repository can use a very small multi-level OFS_DELTA chain to retain extremely large allocations and exhaust memory. This issue is fixed in versions 1.8.6 and 1.9.5."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 5.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-20T18:37:44.115Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/libgit2/libgit2/security/advisories/GHSA-27m5-gxxh-x79j",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/libgit2/libgit2/security/advisories/GHSA-27m5-gxxh-x79j"
        },
        {
          "name": "https://github.com/libgit2/libgit2/commit/0cdfdd5fa8f8514c82413025e1e0808866cf7c30",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libgit2/libgit2/commit/0cdfdd5fa8f8514c82413025e1e0808866cf7c30"
        },
        {
          "name": "https://github.com/libgit2/libgit2/commit/c1896f06df22cc0ca5658df3a8f6cd7ede4cd6ae",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libgit2/libgit2/commit/c1896f06df22cc0ca5658df3a8f6cd7ede4cd6ae"
        },
        {
          "name": "https://github.com/libgit2/libgit2/commit/dec22ac01ad9620c96b7b9ac3ef636ea46d43bed",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libgit2/libgit2/commit/dec22ac01ad9620c96b7b9ac3ef636ea46d43bed"
        },
        {
          "name": "https://github.com/libgit2/libgit2/releases/tag/v1.8.6",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libgit2/libgit2/releases/tag/v1.8.6"
        },
        {
          "name": "https://github.com/libgit2/libgit2/releases/tag/v1.9.5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/libgit2/libgit2/releases/tag/v1.9.5"
        }
      ],
      "source": {
        "advisory": "GHSA-27m5-gxxh-x79j",
        "discovery": "UNKNOWN"
      },
      "title": "libgit2: Unbounded Memory Allocation via Delta Object Result-Size Header"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-53585",
    "datePublished": "2026-08-20T18:37:44.115Z",
    "dateReserved": "2026-06-09T19:11:53.484Z",
    "dateUpdated": "2026-08-20T18:37:44.115Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-53585",
      "date": "2026-08-21",
      "epss": "0.00548",
      "percentile": "0.4367"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-53585\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-20T19:16:54.837\",\"lastModified\":\"2026-08-20T19:16:54.837\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"libgit2 is a portable C implementation of the Git core methods provided as a linkable library with a solid API, allowing to build Git functionality into your application. Prior to 1.8.6 and 1.9.5, git_delta_apply in src/libgit2/delta.c trusts the attacker-controlled res_sz value parsed by hdr_sz from a delta object header and passes that amount to git__malloc before validating delta instructions. Malicious pack data supplied through git_clone, git_fetch, git_remote_fetch, git_indexer_append, or a local attacker-supplied repository can use a very small multi-level OFS_DELTA chain to retain extremely large allocations and exhaust memory. This issue is fixed in versions 1.8.6 and 1.9.5.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"libgit2\",\"product\":\"libgit2\",\"versions\":[{\"version\":\"\u003c 1.8.6\",\"status\":\"affected\"},{\"version\":\"\u003e= 1.9.0, \u003c 1.9.5\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L\",\"baseScore\":5.3,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"LOW\"},\"exploitabilityScore\":3.9,\"impactScore\":1.4}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"references\":[{\"url\":\"https://github.com/libgit2/libgit2/commit/0cdfdd5fa8f8514c82413025e1e0808866cf7c30\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/commit/c1896f06df22cc0ca5658df3a8f6cd7ede4cd6ae\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/commit/dec22ac01ad9620c96b7b9ac3ef636ea46d43bed\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/releases/tag/v1.8.6\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/releases/tag/v1.9.5\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libgit2/libgit2/security/advisories/GHSA-27m5-gxxh-x79j\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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