Description
A Regular-Expression Denial of Service (ReDoS) in the Markdown2. extract_metadata() function (lib/markdown2.py) of trentm markdown2 through v2.5.5 allows attackers to cause a Denial of Service (DoS) via a crafted Markdown document.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | python-markdown2 | No fix yet | — |
| Debian 13 | python-markdown2 | No fix yet | — |
| Debian 12 | python-markdown2 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | python-markdown2 | No fix yet | — |
| Ubuntu 26.04 LTS | python-markdown2 | No fix yet | — |
| Ubuntu 24.04 LTS | python-markdown2 | No fix yet | — |
| Ubuntu 22.04 LTS | python-markdown2 | No fix yet | — |
| Ubuntu 20.04 LTS | python-markdown2 | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-markdown2 | 2.5.5-2.1 | openSUSE-SU-2026:12159-1 |
Advisories 1
- openSUSE-SU-2026:12159-1 python313-markdown2-2.5.5-2.1 on GA media SUSE / openSUSE Security Updates · Oct 17, 2026