CVE-2026-59922
published 2026-07-08CVE-2026-59922: Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character…
PriorityP341high7.5CVSS 3.1
AVNACLPRNUINSUCNINAH
EPSS
0.64%
50.7th percentile
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Affected
26 ranges· showing 25
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| lepture | mistune | < 3.3.0 | 3.3.0 |
| mistune_project | mistune | < 3.3.0 | 3.3.0 |
| mistune_project | mistune | >= 0 < 3.3.0 | 3.3.0 |
| mta | mta-solution-server-rhel9 | — | — |
| rhoai | odh-pipeline-runtime-datascience-cpu-py312-rhel9 | — | — |
| rhoai | odh-pipeline-runtime-minimal-cpu-py312-rhel9 | — | — |
| rhoai | odh-pipeline-runtime-pytorch-cuda-py312-rhel9 | — | — |
| rhoai | odh-pipeline-runtime-pytorch-llmcompressor-cuda-py312-rhel9 | — | — |
| rhoai | odh-pipeline-runtime-pytorch-rocm-py312-rhel9 | — | — |
| rhoai | odh-pipeline-runtime-tensorflow-cuda-py312-rhel9 | — | — |
| rhoai | odh-pipeline-runtime-tensorflow-rocm-py312-rhel9 | — | — |
| rhoai | odh-th06-cpu-torch210-py312-rhel9 | — | — |
| rhoai | odh-th06-cpu-torch291-py312-rhel9 | — | — |
| rhoai | odh-th06-cuda130-torch210-py312-rhel9 | — | — |
| rhoai | odh-th06-cuda130-torch291-py312-rhel9 | — | — |
| rhoai | odh-th06-rocm64-torch291-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-datascience-cpu-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-minimal-cpu-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-minimal-cuda-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-minimal-rocm-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-pytorch-cuda-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-pytorch-rocm-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-tensorflow-cuda-py312-rhel9 | — | — |
| rhoai | odh-workbench-jupyter-tensorflow-rocm-py312-rhel9 | — | — |
CVSS provenance
nvdv3.17.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
vendor_redhat7.5HIGH
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Red Hat
mistune: Mistune: Denial of Service via crafted input
vendor_redhat·2026-07-08·CVSS 7.5
CVE-2026-59922 [HIGH] CWE-1333 mistune: Mistune: Denial of Service via crafted input
mistune: Mistune: Denial of Service via crafted input
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
A flaw was found in Mistune, a Python Markdown parser. A remote attacker could exploit this vulnerability by providing specially crafted input containing specific marker pairs (tilde, equals-sign, or caret). This crafted input causes the parser to perform quadratic work, leading to excessive CPU consumption. This can result in a
GHSA
Mistune plugins/formatting: quadratic-time parsing on long runs of `~~x~~`, `==x==`, and `^^x^^` markers (strikethrough / mark / insert)
ghsa·2026-07-20
CVE-2026-59922 [HIGH] CWE-1333 Mistune plugins/formatting: quadratic-time parsing on long runs of `~~x~~`, `==x==`, and `^^x^^` markers (strikethrough / mark / insert)
Mistune plugins/formatting: quadratic-time parsing on long runs of `~~x~~`, `==x==`, and `^^x^^` markers (strikethrough / mark / insert)
## Summary
**Type:** Algorithmic-complexity denial of service. A run of N closed pairs `~~x~~~~x~~...` (or the analogous `==x==` for `mark`, `^^x^^` for `insert`) causes O(N²) work in the formatting parser. With the `strikethrough`, `mark`, or `insert` plugin enabled, an 8 KB input pegs the CPU for ~4 seconds; 16 KB → ~17 seconds.
**File:** `src/mistune/plugins/formatting.py`, lines 13-15 (the `_STRIKE_END` / `_MARK_END` / `_INSERT_END` patterns and their per-position scan).
**Root cause:** for each opening `~~`/`==`/`^^` the parser scans forward for the matching close pattern. The scan itself uses a bounded regex, but the parser tries the close-scan at
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2026-59922 python-mistune: Mistune: Denial of Service via crafted input [epel-all]
bugzilla·2026-07-28·CVSS 7.5
CVE-2026-59922 [HIGH] CVE-2026-59922 python-mistune: Mistune: Denial of Service via crafted input [epel-all]
CVE-2026-59922 python-mistune: Mistune: Denial of Service via crafted input [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Bugzilla
CVE-2026-59922 python-mistune: Mistune: Denial of Service via crafted input [fedora-all]
bugzilla·2026-07-28·CVSS 7.5
CVE-2026-59922 [HIGH] CVE-2026-59922 python-mistune: Mistune: Denial of Service via crafted input [fedora-all]
CVE-2026-59922 python-mistune: Mistune: Denial of Service via crafted input [fedora-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Bugzilla
CVE-2026-59922 python-mistune08: Mistune: Denial of Service via crafted input [epel-all]
bugzilla·2026-07-28·CVSS 7.5
CVE-2026-59922 [HIGH] CVE-2026-59922 python-mistune08: Mistune: Denial of Service via crafted input [epel-all]
CVE-2026-59922 python-mistune08: Mistune: Denial of Service via crafted input [epel-all]
Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
Bugzilla
CVE-2026-59922 mistune: Mistune: Denial of Service via crafted input
bugzilla·2026-07-08·CVSS 7.5
CVE-2026-59922 [HIGH] CVE-2026-59922 mistune: Mistune: Denial of Service via crafted input
CVE-2026-59922 mistune: Mistune: Denial of Service via crafted input
Mistune is a Python Markdown parser with renderers and plugins. Prior to 3.3.0, a run of closed tilde, equals-sign, or caret marker pairs around a character causes quadratic work in src/mistune/plugins/formatting.py when the strikethrough, mark, or insert plugin scans for matching markers from each possible start position, allowing denial of service through CPU exhaustion. This issue is fixed in version 3.3.0.
2026-07-08
Published