CVE-2026-33762: Github.com/go git/go git/v5 Go-git Missing Validation Decoding Index Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-gm2x-2g9h-ccm8",
  "modified" : "2026-03-31T18:50:23Z",
  "published" : "2026-03-30T17:05:23Z",
  "aliases" : [ "CVE-2026-33762" ],
  "summary" : "go-git missing validation decoding Index v4 files leads to panic",
  "details" : "### Impact\n\n`go-git`’s index decoder for format version 4 fails to validate the path name prefix length before applying it to the previously decoded path name. A maliciously crafted index file can trigger an out-of-bounds slice operation, resulting in a runtime panic during normal index parsing.\n\nThis issue only affects Git index format version 4. Earlier formats (`go-git` supports only `v2` and `v3`) are not vulnerable to this issue.\n\nAn attacker able to supply a crafted `.git/index` file can cause applications using go-git to panic while reading the index. If the application does not recover from panics, this results in process termination, leading to a denial-of-service (DoS) condition.\n\nExploitation requires the ability to modify or inject a Git index file within the local repository in disk. This typically implies write access to the `.git` directory.\n\n### Patches\n\nUsers should upgrade to `v5.17.1`, or the latest `v6` [pseudo-version](https://go.dev/ref/mod#pseudo-versions), in order to mitigate this vulnerability.\n\n### Credit\n\ngo-git maintainers thank @kq5y for finding and reporting this issue privately to the `go-git` project.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/go-git/go-git/v5"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.17.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.17.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/go-git/go-git/security/advisories/GHSA-gm2x-2g9h-ccm8"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33762"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/go-git/go-git"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/go-git/go-git/releases/tag/v5.17.1"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-129" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-03-30T17:05:23Z",
    "nvd_published_at" : "2026-03-31T15:16:15Z"
  }
}