CVE-2024-50338: Git credential manager Git Credential Manager Carriage-return Character Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-86c2-4x57-wc8g",
  "modified" : "2025-01-14T21:59:51Z",
  "published" : "2025-01-14T19:40:54Z",
  "aliases" : [ "CVE-2024-50338" ],
  "summary" : "Git Credential Manager carriage-return character in remote URL allows malicious repository to leak credentials",
  "details" : "### Description\nThe [Git credential protocol](https://git-scm.com/docs/git-credential#IOFMT) is text-based over standard input/output, and consists of a series of lines of key-value pairs in the format `key=value`. Git's documentation restricts the use of the NUL (`\\0`) character and newlines to form part of the keys[^1] or values.\n\nWhen Git reads from standard input, it considers both LF and CRLF[^2] as newline characters for the credential protocol by virtue of [calling `strbuf_getline`](https://github.com/git/git/blob/6a11438f43469f3815f2f0fc997bd45792ff04c0/credential.c#L311) that calls to `strbuf_getdelim_strip_crlf`. Git also validates that a newline is not present in the value by checking for the presence of the line-feed character (LF, `\\n`), and errors if this is the case. This captures both LF and CRLF-type newlines.\n\nGit Credential Manager uses the .NET standard library [`StreamReader`](https://learn.microsoft.com/en-us/dotnet/api/system.io.streamreader?view=net-8.0) class to [read the standard input stream line-by-line](https://github.com/git-ecosystem/git-credential-manager/blob/ae009e11a0fbef804ad9f78816d84a0bc7e052fe/src/shared/Core/StreamExtensions.cs#L138-L141) and parse the `key=value` credential protocol format. The [implementation of the `ReadLineAsync` method](https://github.com/dotnet/runtime/blob/e476b43b5cb42eb44ce23b1c7b793aa361624cf6/src/libraries/System.Private.CoreLib/src/System/IO/StreamReader.cs#L926) considers LF, CRLF, and CR as valid line endings. This is means that .NET considers a single CR as a valid newline character, whereas Git does not.\n\nThis mismatch of newline treatment between Git and GCM means that an attacker can craft a malicious remote URL such as:\n\n```\nhttps://\\rhost=targethost@badhost\n```\n\n..which will be interpreted by Git as:\n\n```\nprotocol=https\nhost=badhost\nusername=\\rhost=targethost\n```\n\nThis will instead be parsed by GCM as if the following has been passed by Git:\n\n```\nprotocol=https\nhost=badhost\nusername=\nhost=targethost\n```\n\nThis results in the `host` field being resolved to the `targethost` value. GCM will then return a credential for `targethost` to Git, which will then send this credential to the `badhost` host.\n\n### Impact\nWhen a user clones or otherwise interacts[^3] with a malicious repository that requires authentication, the attacker can capture credentials for another Git remote. The attack is also heightened when cloning from repositories with submodules when using the `--recursive` clone option as the user is not able to inspect the submodule remote URLs beforehand.\n\n### Patches\nhttps://github.com/git-ecosystem/git-credential-manager/compare/749e287571c78a2b61f926ccce6a707050871ab8...99e2f7f60e7364fe807e7925f361a81f3c47bd1b\n\n### Workarounds\nOnly interacting with trusted remote repositories, and do not clone with `--recursive` to allow inspection of any submodule URLs before cloning those submodules.\n\n### Fixed versions\nThis issue is fixed as of [version 2.6.1](https://github.com/git-ecosystem/git-credential-manager/releases/tag/v2.6.1).\n\n[^1]: The `=` character is also forbidden to form part of the key.\n[^2]: Carriage-return character (CR, `\\r`), followed by a line-feed character.\n[^3]: Any remote operation such as `fetch`, `ls-remote`, etc.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "NuGet",
      "name" : "git-credential-manager"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.6.1"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.6.0"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/git-ecosystem/git-credential-manager/security/advisories/GHSA-86c2-4x57-wc8g"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2024-50338"
  }, {
    "type" : "WEB",
    "url" : "https://git-scm.com/docs/git-credential#IOFMT"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/dotnet/runtime/blob/e476b43b5cb42eb44ce23b1c7b793aa361624cf6/src/libraries/System.Private.CoreLib/src/System/IO/StreamReader.cs#L926"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/git-ecosystem/git-credential-manager"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/git-ecosystem/git-credential-manager/blob/ae009e11a0fbef804ad9f78816d84a0bc7e052fe/src/shared/Core/StreamExtensions.cs#L138-L141"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/git-ecosystem/git-credential-manager/compare/749e287571c78a2b61f926ccce6a707050871ab8...99e2f7f60e7364fe807e7925f361a81f3c47bd1b"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/git-ecosystem/git-credential-manager/releases/tag/v2.6.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/git/git/blob/6a11438f43469f3815f2f0fc997bd45792ff04c0/credential.c#L311"
  }, {
    "type" : "WEB",
    "url" : "https://learn.microsoft.com/en-us/dotnet/api/system.io.streamreader?view=net-8.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-436" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-01-14T19:40:54Z",
    "nvd_published_at" : "2025-01-14T19:15:31Z"
  }
}