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Vulnerabilities

Vulnerability · CVE-2026-27135

nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C.

Published Mar 18, 2026 · catalog updated Oct 15, 2026 · Red Hat

Check if you run it

No confirmed exploitation is on record for CVE-2026-27135. EPSS is 0.93%. Act only if a listed version of Red Hat is installed.

Gaps on this record

  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.5
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.93%
Remediation
Advisory link
Affected products
cpe nghttp2/nghttp2

nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. Prior to version 1.68.1, the nghttp2 library stops reading the incoming data when user facing public API or is called by the application. They might be called internally by the library when it detects the situation that is subject to connection error. Due to the missing internal state validation, the library keeps reading the rest of the data after one of those APIs is called. Then receiving a malformed frame that causes FRAME_SIZE_ERROR causes assertion failure. nghttp2 v1.68.1 adds missing state validation to avoid assertion failure. No known workarounds are available.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe nghttp2/nghttp2version unspecified

How to fix CVE-2026-27135

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-27135. EPSS is 0.93%. Act only if a listed version of Red Hat is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-617. EPSS 0.93%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 18, 2026 · NIST NVD

    Detected

    nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. Prior to version 1.68.1, the nghttp2 library stops reading the incoming data when user facing public API or is called by the application. They might be called internally by the library when it detects the situation that is subject to connection error. Due to the missing internal state validation, the library keeps read

  2. Oct 15, 2026 · NIST NVD

    Updated

    nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. Prior to version 1.68.1, the nghttp2 library stops reading the incoming data when user facing public API or is called by the application. They might be called internally by the library when it detects the situation that is subject to connection error. Due to the missing internal state validation, the library keeps read

Sources

  • CSAF AdvisoriesVendor advisoryRHSA-2026:9711:CVE-2026-27135

    A flaw was found in nghttp2. Due to missing internal state validation, the library continues to process incoming data even after a session has been terminated. A remote attacker could exploit this by sending a specially crafted HTTP/2 frame, leading to an assertion failure and a

    security.access.redhat.com
  • CSAF AdvisoriesVendor advisoryRHSA-2026:9832:CVE-2026-27135

    A flaw was found in nghttp2. Due to missing internal state validation, the library continues to process incoming data even after a session has been terminated. A remote attacker could exploit this by sending a specially crafted HTTP/2 frame, leading to an assertion failure and a

    security.access.redhat.com
  • CSAF AdvisoriesVendor advisoryRHSA-2026:9874:CVE-2026-27135

    A flaw was found in nghttp2. Due to missing internal state validation, the library continues to process incoming data even after a session has been terminated. A remote attacker could exploit this by sending a specially crafted HTTP/2 frame, leading to an assertion failure and a

    security.access.redhat.com
  • CVE.orgVulnerability recordCVE-2026-27135

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-27135

    30-day exploitation probability 0.9%

    first.org
  • NIST NVDVulnerability recordCVE-2026-27135

    nghttp2 is an implementation of the Hypertext Transfer Protocol version 2 in C. Prior to version 1.68.1, the nghttp2 library stops reading the incoming data when user facing public API or is called by the ap

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.