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Symfony Routing components CompiledUrlMatcher and UrlMatcher interpret the host and path…

sensiolabs symfony · CVE-2026-118516 CVE-2026-123792 ETK-2026-3492 ETK-2026-3494 ETK-2026-3495 ETK-2026-3733 EUVD-2026-118309 GHSA-3H27-HJV7-FQJX GHSA-5MX8-MWRP-5693 GHSA-6PRC-H956-HXJQ GHSA-8F57-M8WJ-X65W GHSA-C7HM-WQWP-F9V8 GHSA-CPWW-5VPX-72X7 GHSA-HWFG-QWVH-2WFX GHSA-PXJ9-JH84-VHM5 GHSA-XQW3-X93M-887X
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Assessment: Track

SSVC decision points: exploitation none, automatable yes, technical impact partial, deployment low.

What is it?

The Symfony Yaml components Inline and Parser, parse some YAML documents inefficiently, so that a small crafted document can take disproportionately long to process, keeping a PHP process busy for seconds or minutes, potentially causing a denial of service in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11. The parser repeats work it has already done in several places. An embedded mapping in a flow sequence is parsed again for every scalar appended to it, and so are the collections nested in it, so the parse time grows exponentially with the nesting depth. The patterns matching mapping keys and tags scan a run of spaces once per character of the run, and each scalar of a flow collection is matched against a copy of the rest of the collection, so the parse time grows quadratically with the size of the input. Nested blocks are also copied at each nesting level, which consumes memory as well as time. A few other constructs, such as an empty sequence item followed by a blank line or an anchor named 0, trigger similar repeated work. Any code parsing untrusted YAML is affected, with the default flags. In Symfony 7.4 and later, that i

Evidence

No coverage recorded yet.

Exploitation

  • Exploit code published (not verified by us)
  • Exploited in the wild (confirmed by a source)
  • Listed as known exploited (CISA KEV)
CVSS
8.7
EPSS
0.5%
First seen
7 d ago
Status
corroborated

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