CVE-2026-48979Network attack vector

Request smuggling via mismatched HTTP/2 content length

Published Jun 17, 2026 · Updated Jun 17, 2026

HTTP request smuggling in PHP Standard Library h2 6.1.0, 6.1.1 and 6.2.0 allows remote attackers to bypass application size limits. Psl\H2\ServerConnection accepts DATA payload totals that differ from the content-length declared in HEADERS, instead of rejecting mismatches or overflow. Exposure requires direct use of ServerConnection for untrusted client traffic; documented high-level APIs are unaffected, while excess bytes can reach application processing.

CVSS severity7.5
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in PHP Standard Library h2 6.1.0, 6.1.1 and 6.2.0 allows remote attackers to bypass application size limits. Psl\H2\ServerConnection accepts DATA payload totals that differ from the content-length declared in HEADERS, instead of rejecting mismatches or overflow. Exposure requires direct use of ServerConnection for untrusted client traffic; documented high-level APIs are unaffected, while excess bytes can reach application processing.

The record

CVE
CVE-2026-48979
Published
Jun 17, 2026
Updated
Jun 17, 2026
Vendor
PHP Standard Library
Product
PHP Standard Library
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 6.1.0, < 6.1.2
  2. Affected versionversion=>= 6.2.0, < 6.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PHP Standard Library · PHP Standard Libraryversion=>= 6.1.0, < 6.1.2; version=>= 6.2.0, < 6.2.1
PHP Standard Library · h2version=>= 6.1.0, < 6.1.2; version=>= 6.2.0, < 6.2.1

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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