Description
In mistune through 2.0.2, support of inline markup is implemented by using regular expressions that can involve a high amount of backtracking on certain edge cases. This behavior is commonly named catastrophic backtracking.
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 | mistune | 2.0.3-1 | — |
| Debian 13 | mistune | 2.0.3-1 | — |
| Debian 12 | mistune | 2.0.3-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | mistune | No fix yet | — |
| Ubuntu 20.04 LTS | mistune | No fix yet | — |
| Ubuntu 18.04 LTS | mistune | No fix yet | — |
| Ubuntu 16.04 LTS | mistune | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Ceph Storage 8 | ceph +27 | 2:19.2.1-331.el9cp | RHSA-2026:2711 |
| Red Hat Ceph Storage 8 | thrift +5 | 0.20.0-4.el9cp | RHSA-2026:2711 |
| Red Hat Ceph Storage 7 | ceph +25 | 2:18.2.1-381.el8cp | RHSA-2026:2769 |
| Red Hat Ceph Storage 7 | cephadm | 2:18.2.1-381.el9cp | RHSA-2026:2769 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-mistune | 3.1.0-1.1 | openSUSE-SU-2025:14637-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | py3-mistune | 2.0.3-r0 | — |
| Alpine v3.23 | py3-mistune | 2.0.3-r0 | — |
| Alpine v3.22 | py3-mistune | 2.0.3-r0 | — |
| Alpine v3.21 | py3-mistune | 2.0.3-r0 | — |
| Alpine v3.20 | py3-mistune | 2.0.3-r0 | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | py3-mistune | 2.0.3-r0 | — |
| Alpine v3.18 | py3-mistune | 2.0.3-r0 | — |
| Alpine v3.17 | py3-mistune | 2.0.3-r0 | — |
| Alpine v3.16 | py3-mistune | 2.0.3-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | python-mistune | 0.8.3-5 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | mistune | >= 2.0.0a1, < 2.0.3 | 2.0.3 | GHSA-fw3v-x4f2-v673 |
Advisories 3
- RHSA-2026:2769 Red Hat Security Advisory: Red Hat Ceph Storage 7.1 security and bug fix updates Red Hat Security Advisories (RHSA) · Oct 20, 2026
- RHSA-2026:2711 Red Hat Security Advisory: Red Hat Ceph Storage 8.1 security and bug fix update Red Hat Security Advisories (RHSA) · Oct 20, 2026
- openSUSE-SU-2025:14637-1 python311-mistune-3.1.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026