CVE-2026-86434 commonmark 2.0.0 through 2.8.3 Denial of Service via Slug Collision

league/commonmark versions = 2.0.0 and 2.8.4 patched in 2.9.0 contain a denial of service vulnerability in UniqueSlugNormalizer::normalize, which restarts its numeric-suffix search from 1 on every slug collision, resulting in OK^2 time complexity for K headings that collapse to the same base slug...

CVE-2026-86435

commonmark versions from 1.5.0 before 2.9.0 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessiv...

CVE-2026-86434 commonmark 2.0.0 through 2.8.3 Denial of Service via Slug Collision

league/commonmark versions = 2.0.0 and 2.8.4 patched in 2.9.0 contain a denial of service vulnerability in UniqueSlugNormalizer::normalize, which restarts its numeric-suffix search from 1 on every slug collision, resulting in OK^2 time complexity for K headings that collapse to the same base slug...

CVE-2026-86435

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessiv...

CVE-2026-86434

league/commonmark versions = 2.0.0 and 2.8.4 patched in 2.9.0 contain a denial of service vulnerability in UniqueSlugNormalizer::normalize, which restarts its numeric-suffix search from 1 on every slug collision, resulting in OK^2 time complexity for K headings that collapse to the same base slug...

CVE-2026-86435 commonmark 1.5.0 before 2.8.4 Denial of Service via Footnote

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessiv...

EUVD-2026-72393

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Footnote extension that fails to deduplicate footnote definitions. Attackers can craft documents with duplicate footnote definitions and references to create quadratic output expansion, consuming excessiv...

EUVD-2026-72392

league/commonmark versions = 2.0.0 and 2.8.4 patched in 2.9.0 contain a denial of service vulnerability in UniqueSlugNormalizer::normalize, which restarts its numeric-suffix search from 1 on every slug collision, resulting in OK^2 time complexity for K headings that collapse to the same base slug...

CVE-2026-86435

CVE-2026-86435 affects the PHP League/commonmark library (versions 1.5.0 through before 2.8.4) in its Footnote extension . The root cause is a failure to deduplicate footnote definitions, allowing an attacker to craft a document containing duplicate footnote definitions and references that trigge...

CVE-2026-86434 commonmark 2.0.0 through 2.8.3 Denial of Service via Slug Collision

league/commonmark versions = 2.0.0 and 2.8.4 patched in 2.9.0 contain a denial of service vulnerability in UniqueSlugNormalizer::normalize, which restarts its numeric-suffix search from 1 on every slug collision, resulting in OK^2 time complexity for K headings that collapse to the same base slug...

CVE-2026-86434

league/commonmark (PHP) versions ≥ 2.0.0 and

CVE-2026-86433

commonmark versions from 1.5.0 before 2.9.0 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks t...

CVE-2026-86433

commonmark (PHP Markdown parser) versions 1.5.0 through 2.8.3 contain a denial-of-service vulnerability in the Attributes extension . The root cause is that AttributesListener::findTargetAndDirection() performs quadratic-time sibling list scanning , allowing an unauthenticated attacker to submit ...

CVE-2026-86433

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks t...

CVE-2026-86433 commonmark 1.5.0 before 2.8.4 Denial of Service via Attributes

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks t...

EUVD-2026-72391

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks t...

CVE-2026-86433 commonmark 1.5.0 before 2.8.4 Denial of Service via Attributes

commonmark versions from 1.5.0 before 2.8.4 contain a denial of service vulnerability in the Attributes extension where AttributesListener::findTargetAndDirection performs quadratic-time sibling list scanning. Unauthenticated attackers can submit approximately 32 KB of repeated attribute blocks t...

CVE-2026-86431 commonmark before 2.9.1 XSS via AttributesExtension form feed bypass

league/commonmark thephpleague/commonmark versions = 2.7.0 and 2.9.1 contain a cross-site scripting vulnerability in the AttributesExtension. Prefixing an attribute name with a single U+000C form feed byte e.g. \x0Conclick="alert1" bypasses the AttributesHelper::filterAttributes 'on' event-handle...

CVE-2026-86431

league/commonmark (thephpleague/commonmark) versions >= 2.7.0 and

EUVD-2026-72390

commonmark versions from 2.0.0 before 2.8.4 contain a denial of service vulnerability in XmlRenderer that emits depth-proportional indentation for every XML tag. Attackers can provide deeply nested Markdown or AST structures to cause quadratic memory consumption and output amplification, exhausti...