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CVE-2026-65100 Apache CVE debrief

Apache Traffic Server is vulnerable to a corruption of subsequent header blocks on a connection due to an encoder synchronization issue with the peer decoder after an HTTP/2 HPACK dynamic table update failure. This issue arises from the server's handling of HTTP/2 HPACK dynamic table updates before confirming the header block has been encoded successfully. The vulnerability can lead to an encoder being out of sync with the peer decoder, causing subsequent header blocks on the connection to be corrupted. Users of affected versions should be aware of the potential for traffic processing impacts and take action to upgrade to a fixed version.

Vendor
Apache
Product
Traffic Server
CVSS
MEDIUM 6.3
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-29
Original CVE updated
2026-08-03
Advisory published
2026-07-29
Advisory updated
2026-08-03

Who should care

Users of Apache Traffic Server versions 8.0.0 through 8.1.9, 9.0.0 through 9.2.14, and 10.0.0 through 10.1.3 should be aware of this vulnerability and take action to upgrade to a fixed version. Operators, security teams, and platform administrators managing affected deployments should prioritize this vulnerability due to its potential impact on traffic processing.

Technical summary

The vulnerability in Apache Traffic Server arises from updating the HTTP/2 HPACK dynamic table before confirming the header block has been encoded successfully. This can lead to an encoder being out of sync with the peer decoder, causing subsequent header blocks on the connection to be corrupted. The issue affects Apache Traffic Server versions 8.0.0 through 8.1.9, 9.0.0 through 9.2.14, and 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4 for a fix.

Defensive priority

Medium priority due to the CVSS score of 6.3 and potential for impacting traffic processing.

Recommended defensive actions

  • Upgrade to Apache Traffic Server version 9.2.15 or 10.1.4
  • Review and update affected versions 8.0.0 through 8.1.9, 9.0.0 through 9.2.14, and 10.0.0 through 10.1.3
  • Monitor for potential exploitation attempts
  • Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
  • Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
  • Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review

Evidence notes

The CVE record and NVD entry provide details on the vulnerability affecting Apache Traffic Server versions 8.0.0 through 8.1.9, 9.0.0 through 9.2.14, and 10.0.0 through 10.1.3. Users are recommended to upgrade to version 9.2.15 or 10.1.4 for a fix. Evidence is limited to CVE and NVD details. Defenders should verify affected versions and plan for upgrades or mitigations.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-65100 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-65100

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-65100 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-65100

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.