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CVE-2026-55766

guzzlehttp/psr7 is a PSR-7 HTTP message library implementation in PHP. Prior to 2.12.1, guzzlehttp/psr7 did not reject CR/LF characters in certain first-party HTTP start-line fields: the request method, protocol version, and response reason phrase. If an application placed attacker-controlled data into one of those fields and later serialized the PSR-7 message as raw HTTP/1.x, for example with Message::toString() or an equivalent serializer, the serialized message could contain attacker-controll
Lifecycle PUBLISHED1 preserved revisionFact urn:baitaphish:canonical-cve-fact-revision:v2:580f0049d2d091b28e8c6f0034a254e4860b1c32e6c910adb82a5f55772034c2
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
1

Preserved source conflicts

No provider value was silently selected as the winner.

cwe · 2 assertions

{"cweId":"CWE-93","description":"CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4c428eb57186450194822c9d2ec9ccbfcca84b7707d4899ea32382d1a257bc9 · sha256:1bac3bdea5350c67… · /containers/cna/problemTypes/0/descriptions/0

{"cweId":"CWE-113","description":"CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')","lang":"en","type":"CWE"}

  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4c428eb57186450194822c9d2ec9ccbfcca84b7707d4899ea32382d1a257bc9 · sha256:1bac3bdea5350c67… · /containers/cna/problemTypes/1/descriptions/0

Affected products and versions

1 source assertion
{"product":"psr7","vendor":"guzzle","versions":[{"status":"affected","version":"< 2.12.1"}]}
  • cve_program_cvelist_v5affected
    urn:baitaphish:normalized-source-record:v2:c4c428eb57186450194822c9d2ec9ccbfcca84b7707d4899ea32382d1a257bc9 · sha256:1bac3bdea5350c67… · /containers/cna/affected/0

Provider-owned CVSS observations

1 source assertion
{"metric":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":4.8,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N","version":"3.1"},"metric_type":"cvssV3_1"}
  • cve_program_cvelist_v5cvss
    urn:baitaphish:normalized-source-record:v2:c4c428eb57186450194822c9d2ec9ccbfcca84b7707d4899ea32382d1a257bc9 · sha256:1bac3bdea5350c67… · /containers/cna/metrics/0/cvssV3_1

CWE assertions

2 source assertions
{"cweId":"CWE-93","description":"CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4c428eb57186450194822c9d2ec9ccbfcca84b7707d4899ea32382d1a257bc9 · sha256:1bac3bdea5350c67… · /containers/cna/problemTypes/0/descriptions/0
{"cweId":"CWE-113","description":"CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')","lang":"en","type":"CWE"}
  • cve_program_cvelist_v5cwe
    urn:baitaphish:normalized-source-record:v2:c4c428eb57186450194822c9d2ec9ccbfcca84b7707d4899ea32382d1a257bc9 · sha256:1bac3bdea5350c67… · /containers/cna/problemTypes/1/descriptions/0

Source references

1 source assertion
{"name":"https://github.com/guzzle/psr7/security/advisories/GHSA-vm85-hxw5-5432","tags":["x_refsource_CONFIRM"],"url":"https://github.com/guzzle/psr7/security/advisories/GHSA-vm85-hxw5-5432"}
  • cve_program_cvelist_v5reference
    urn:baitaphish:normalized-source-record:v2:c4c428eb57186450194822c9d2ec9ccbfcca84b7707d4899ea32382d1a257bc9 · sha256:1bac3bdea5350c67… · /containers/cna/references/0

Attribution and limitations

  • CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →

Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.

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