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VulnerabilityPublished

league/commonmark: Denial of service via adjacent inline attribute blocks

Affects league/commonmarkSource GCVE Database

0

CVSS 7.5 High : upgrade to 2.9.0 soon.

Data as of 7 Aug 2026, 06:11 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 2.9.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What to do

Upgrade league/commonmark to 2.9.0.

Affected software

ProductAffectedFixed in
Packagistleague/commonmarkAffected
  • >=1.5.0 <2.9.0
Fixed in
  • 2.9.0

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AI-suggested

A patch is available for this vulnerability. Users are advised to upgrade to a fixed version of league/commonmark at or beyond 2.9.0. If upgrading is not immediately possible, mitigations include disabling the Attributes extension for untrusted input or enforcing strict maximum input length limits to reduce exposure to the quadratic parsing behavior.

Description

A denial of service vulnerability exists in league/commonmark when the Attributes extension is enabled. The vulnerability arises from a quadratic time complexity in resolving adjacent inline attribute blocks at the start of a block, causing excessive CPU usage. An unauthenticated attacker can exploit this by submitting crafted input that triggers long processing times, impacting availability. This affects all versions from 1.5.0 up to but not including 2.9.0. A patch is available to address this issue.

References

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