CVE-2026-55766: guzzlehttp/psr7: CRLF Injection in HTTP Start-Line Serialization

medium Affects guzzlehttp/psr7. Feed 2026.10.29.4, updated 2026-10-29; published 2026-06-19; advisory modified 2026-09-10.

guzzlehttp/psr7: CRLF Injection in HTTP Start-Line Serialization

Package: guzzlehttp/psr7 Composer
Affected versions: <2.12.1
Fixed in: 2.12.1
Severity: medium CVSS 4.8
Exploitation: not on CISA KEV · EPSS 0% (13.8th percentile)
Published: 2026-06-19
Source: osv.dev

References

CWE-113 CWE-93

NVD record guzzlehttp/psr7 advisories

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Related advisories

CVE-2022-24775 medium Improper Input Validation in guzzlehttp/psr7 same package: guzzlehttp/psr7
CVE-2023-29197 medium Improper header name validation in guzzlehttp/psr7 same package: guzzlehttp/psr7
CVE-2026-59882 medium guzzlehttp/psr7: Host Confusion via Weak URI Host Validation same package: guzzlehttp/psr7
CVE-2026-48998 medium guzzlehttp/psr7 has Host Confusion via Authority Reinterpretation same package: guzzlehttp/psr7
CVE-2026-49214 medium guzzlehttp/psr7 has CRLF Injection via URI Host Component same package: guzzlehttp/psr7
CVE-2009-1149 high phpMyAdmin HTTP Response Splitting Vulnerability same weakness: CWE-113