{
  "cveId": "CVE-2023-26485",
  "url": "https://patchblox.com/security/cve/CVE-2023-26485",
  "summary": "CVE-2023-26485 is fixed in 10 products on 1 platform, first by cmark-gfm 0.29.0.gfm.0-4ubuntu0.1~esm1, released March 31, 2023. It is not reported as exploited. Patch Radar priority: High.",
  "title": "cmark-gfm: cmark-gfm is GitHub\u0027s fork of cmark, a CommonMark parsing and renderinglibrary and program in C",
  "description": "cmark-gfm is GitHub\u0027s fork of cmark, a CommonMark parsing and renderinglibrary and program in C. A polynomial time complexity issue in cmark-gfmmay lead to unbounded resource exhaustion and subsequent denial of service.This CVE covers quadratic complexity issues when parsing text which leadswith either large numbers of \u0060_\u0060 characters. This issue has been addressedin version 0.29.0.gfm.10. Users are advised to upgrade. Users unable toupgrade should validate that their input comes from trusted sources.### ImpactA polynomial time complexity issue in cmark-gfm may lead to unboundedresource exhaustion and subsequent denial of service.### Proof of concept\u0060\u0060\u0060$ ~/cmark-gfm$ python3 -c \u0027pad = \u0022_\u0022 * 100000; print(pad \u002B \u0022.\u0022 \u002B pad,end=\u0022\u0022)\u0027 | time ./build/src/cmark-gfm --to plaintext\u0060\u0060\u0060Increasing the number 10000 in the above commands causes the running timeto increase quadratically.### PatchesThis vulnerability have been patched in 0.29.0.gfm.10.### Note on cmark and cmark-gfmXXX: TBD[cmark-gfm](https://github.com/github/cmark-gfm) is a fork of[cmark](https://github.com/commonmark/cmark) that adds the GitHub FlavoredMarkdown extensions. The two codebases have diverged over time, but share acommon core. These bugs affect both \u0060cmark\u0060 and \u0060cmark-gfm\u0060.### CreditWe would like to thank @gravypod for reporting this vulnerability.### Referenceshttps://en.wikipedia.org/wiki/Time_complexity### For more informationIf you have any questions or comments about this advisory:* Open an issue in [github/cmark-gfm](https://github.com/github/cmark-gfm)",
  "published": "2023-03-31T16:15:00Z",
  "severity": "Medium",
  "cvss": 7.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "epss": 0.01029,
  "epssPercentile": 0.63922,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "fixes": [
    {
      "platform": "linux",
      "product": "cmark-gfm",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "0.29.0.gfm.13-1",
      "fix": "DEBIAN-CVE-2023-26485",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-26485",
      "released": "2023-03-31T23:15:07Z"
    },
    {
      "platform": "linux",
      "product": "cmark-gfm",
      "release": "Debian 14",
      "fixedVersion": "0.29.0.gfm.13-1",
      "fix": "DEBIAN-CVE-2023-26485",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-26485",
      "released": "2023-03-31T23:15:07Z"
    },
    {
      "platform": "linux",
      "product": "cmark-gfm",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "0.29.0.gfm.0-4ubuntu0.1~esm1",
      "fix": "cmark-gfm 0.29.0.gfm.0-4ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-cmark-gfm-0.29.0.gfm.0-4ubuntu0.1-esm1",
      "released": "2023-03-31T16:15:00Z"
    },
    {
      "platform": "linux",
      "product": "cmark-gfm",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "0.29.0.gfm.3-3ubuntu0.1~esm1",
      "fix": "cmark-gfm 0.29.0.gfm.3-3ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-cmark-gfm-0.29.0.gfm.3-3ubuntu0.1-esm1",
      "released": "2023-03-31T16:15:00Z"
    },
    {
      "platform": "linux",
      "product": "cmark-gfm",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "0.29.0.gfm.6-6ubuntu0.24.04.1~esm1",
      "fix": "cmark-gfm 0.29.0.gfm.6-6ubuntu0.24.04.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-cmark-gfm-0.29.0.gfm.6-6ubuntu0.24.04.1-esm1",
      "released": "2023-03-31T16:15:00Z"
    },
    {
      "platform": "linux",
      "product": "cmark-gfm",
      "release": "Ubuntu 24.10 (oracular)",
      "fixedVersion": "0.29.0.gfm.6-6ubuntu0.24.10.1",
      "fix": "cmark-gfm 0.29.0.gfm.6-6ubuntu0.24.10.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-oracular-cmark-gfm-0.29.0.gfm.6-6ubuntu0.24.10.1",
      "released": "2026-01-16T01:42:23Z"
    },
    {
      "platform": "linux",
      "product": "libcmark-gfm-extensions0",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "0.29.0.gfm.0-4ubuntu0.1~esm1",
      "fix": "libcmark-gfm-extensions0 0.29.0.gfm.0-4ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libcmark-gfm-extensions0-0.29.0.gfm.0-4ubuntu0.1-esm1",
      "released": "2023-03-31T16:15:00Z"
    },
    {
      "platform": "linux",
      "product": "libcmark-gfm-extensions0.29.0.gfm.3",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
      "fixedVersion": "0.29.0.gfm.3-3ubuntu0.1~esm1",
      "fix": "libcmark-gfm-extensions0.29.0.gfm.3 0.29.0.gfm.3-3ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-libcmark-gfm-extensions0.29.0.gfm.3-0.29.0.gfm.3-3ubuntu0.1-esm1",
      "released": "2023-03-31T16:15:00Z"
    },
    {
      "platform": "linux",
      "product": "libcmark-gfm-extensions0.29.0.gfm.6",
      "release": "Ubuntu 24.04.5 LTS (noble)",
      "fixedVersion": "0.29.0.gfm.6-6ubuntu0.24.04.1~esm1",
      "fix": "libcmark-gfm-extensions0.29.0.gfm.6 0.29.0.gfm.6-6ubuntu0.24.04.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-noble-libcmark-gfm-extensions0.29.0.gfm.6-0.29.0.gfm.6-6ubuntu0.24.04.1-esm1",
      "released": "2023-03-31T16:15:00Z"
    },
    {
      "platform": "linux",
      "product": "libcmark-gfm-extensions0.29.0.gfm.6",
      "release": "Ubuntu 24.10 (oracular)",
      "fixedVersion": "0.29.0.gfm.6-6ubuntu0.24.10.1",
      "fix": "libcmark-gfm-extensions0.29.0.gfm.6 0.29.0.gfm.6-6ubuntu0.24.10.1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-oracular-libcmark-gfm-extensions0.29.0.gfm.6-0.29.0.gfm.6-6ubuntu0.24.10.1",
      "released": "2026-01-16T01:42:23Z"
    },
    {
      "platform": "linux",
      "product": "libcmark-gfm0",
      "release": "Ubuntu 20.04 LTS (focal)",
      "fixedVersion": "0.29.0.gfm.0-4ubuntu0.1~esm1",
      "fix": "libcmark-gfm0 0.29.0.gfm.0-4ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-focal-libcmark-gfm0-0.29.0.gfm.0-4ubuntu0.1-esm1",
      "released": "2023-03-31T16:15:00Z"
    },
    {
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      "product": "libcmark-gfm0.29.0.gfm.3",
      "release": "Ubuntu 22.04.1 LTS (jammy)",
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      "fix": "libcmark-gfm0.29.0.gfm.3 0.29.0.gfm.3-3ubuntu0.1~esm1",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-jammy-libcmark-gfm0.29.0.gfm.3-0.29.0.gfm.3-3ubuntu0.1-esm1",
      "released": "2023-03-31T16:15:00Z"
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      "url": "https://patchblox.com/security/fix/linux/ubuntu-oracular-libcmark-gfm0.29.0.gfm.6-0.29.0.gfm.6-6ubuntu0.24.10.1",
      "released": "2026-01-16T01:42:23Z"
    },
    {
      "platform": "linux",
      "product": "python-cmarkgfm",
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      "fixedVersion": "2024.11.20-1",
      "fix": "DEBIAN-CVE-2023-26485",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2023-26485",
      "released": "2023-03-31T23:15:07Z"
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      "released": "2023-03-31T23:15:07Z"
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      "released": "2023-03-31T23:15:07Z"
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      "released": "2023-03-31T23:15:07Z"
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  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-08T19:12:23Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
  }
}