CVE-2026-111808: Apache Traffic Server can be used to exhaust an HTTP/1.1 origin's worker pool via a malformed padded HTTP/2 DATA frame
CVE-2026-111808 key facts
- CISA KEV
- Not listed (catalogue checked )
- Highest advisory rating
- High
- CVSS base score
- 8.6 (Red Hat), 7.7 (Apache)
- Weakness
- CWE-130
- Fixed releases
- Apache: 9.2.16, 10.1.5, 10.2.1
- Red Hat: 9.2.16, 10.1.5, 10.2.1
- Listed by VulniPulse
- Record changed
Ratings, versions and fixes are quoted from the vendor advisories that cover only CVE-2026-111808; each belongs to its advisory, not to every product listed. How records are collected and checked.
How do I fix CVE-2026-111808?
Upgrade to a fixed release named by the vendor:
- Apache: 9.2.16, 10.1.5, 10.2.1
- Red Hat: 9.2.16, 10.1.5, 10.2.1
- Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue. (Apache)
- Upgrade Apache Traffic Server to 9.2.16, 10.1.5, or 10.2.1. As a workaround, disabling HTTP/2 on the proxy (proxy.config.http2.enabled) or restricting HTTP/2 client access reduces exposure to backend worker-pool exhaustion. (Red Hat)
Vendor advisories for CVE-2026-111808
Apache
1 advisory- Advisory severityHigh7.7
High [CVE-2026-111808] Apache Traffic Server can be used to exhaust an HTTP/1.1 origin's worker pool via a malformed padded HTTP/2 DATA frame
CVE-2026-111808Source published Source updated
Apache Traffic Server can be used to exhaust an HTTP/1.1 origin's worker pool via a malformed padded HTTP/2 DATA frame. This issue affects Apache Traffic Server: from 8.0.0 through 8.1.11, from 9.0.0 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0. Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.
- Affected products in this advisory
- Apache Traffic Server
- Source-reported affected versions
- 8.0.0 through 8.1.11
- 9.0.0 through 9.2.15
- 10.0.0 through 10.1.4
- Source-reported fixed versions
- 9.2.16
- 10.1.5
- 10.2.1
- Mitigation guidance
- Users are recommended to upgrade to version 9.2.16, 10.1.5, or 10.2.1, which fix the issue.
Red Hat
1 advisory- Advisory severityHigh8.6
High [CVE-2026-111808] Denial of Service via malformed padded HTTP/2 DATA frame
CVE-2026-111808Source published Source updated
Denial of Service via malformed padded HTTP/2 DATA frame. Red Hat rates this important (CVSS 8.6). Weakness: CWE-130.
- Related products — impact not confirmed
- No product details extracted. Check the source bulletin.
- Source-reported affected versions
- 8.0.0
- 8.1.11
- 9.0.0
- 9.2.15
3 more entries in the full advisory.
- Source-reported fixed versions
- 9.2.16
- 10.1.5
- 10.2.1
- Mitigation guidance
- Upgrade Apache Traffic Server to 9.2.16, 10.1.5, or 10.2.1. As a workaround, disabling HTTP/2 on the proxy (proxy.config.http2.enabled) or restricting HTTP/2 client access reduces exposure to backend worker-pool exhaustion.
References
More Apache advisories
CVE-2026-112381Oct 21, 2026Apache Traffic Server can crash with a null pointer dereferenceCVE-2026-111817Oct 21, 2026Apache Traffic Server can stall a chunked transferCVE-2026-111812Oct 21, 2026Apache Traffic Server's origin_server_auth plugin lets a client force signingCVE-2026-111811Oct 21, 2026Apache Traffic Server's experimental tsmemcache pluginCVE-2026-111809Oct 21, 2026Apache Traffic ServerCVE-2026-111810Oct 21, 2026Apache Traffic Server 9.2.15, 10.1.4 and 10.2.0 write one unthrottled diagnostic log line
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