PHP Standard Library: HTTP/2 server-side missing content-length validation enables request smuggling

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Summary

CVECVE-2026-48979
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-17 21:16:23 UTC
Updated2026-06-18 14:17:28 UTC
DescriptionPHP Standard Library (PSL) is set of APIs covering async, collections, networking, I/O, cryptography, terminal UI, etc. In versions 6.1.0, 6.1.1 and 6.2.0, the Psl\H2\ServerConnection does not validate that the total bytes received in DATA frames match the content-length header declared in the HEADERS frame, allowing request smuggling. This is in violation of RFC 9113 §8.1.1. A malicious client is able to send more DATA bytes than declared, smuggling additional content past application-level size limits and send fewer DATA bytes than declared and close the stream early, causing applications that trust the declared length to behave incorrectly. The vulnerability is only reachable for consumers using Psl\H2\ServerConnection directly to accept untrusted client traffic. Consumers of documented high-level PSL APIs are not affected. This issue has been fixed in versions 6.1.2 and 6.2.1.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS: 0.002670000 probability, percentile 0.180390000 (date 2026-06-21)

Problem Types: CWE-444 | CWE-444 CWE-444: Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
3.1CNADECLARED7.5HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Php-standard-library Php-standard-library affected >= 6.1.0, < 6.1.2 Not specified
CNA Php-standard-library Php-standard-library affected >= 6.2.0, < 6.2.1 Not specified
CNA Php-standard-library Php-standard-library/h2 affected >= 6.1.0, < 6.1.2 Not specified
CNA Php-standard-library Php-standard-library/h2 affected >= 6.2.0, < 6.2.1 Not specified

References

ReferenceSourceLinkTags
github.com/php-standard-library/php-standard-library/releases/tag/6.2.1 [email protected] github.com
github.com/php-standard-library/php-standard-library/releases/tag/6.1.2 [email protected] github.com
github.com/php-standard-library/php-standard-library/security/advisories... [email protected] github.com
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