CVE-2026-111817: Apache Traffic Server can stall a chunked transfer that it passes through with its trailers removed (proxy.config.http.drop_chunked_trailers) until the connection times out, because it waits for the trailer bytes it has already dropped
CVE-2026-111817 key facts
- CISA KEV
- Not listed (catalogue checked )
- Highest advisory rating
- Medium
- CVSS base score
- 6.9 (Apache), 5.3 (Red Hat)
- Weakness
- CWE-444
- Fixed releases
- Apache: 10.1.5, 10.2.1
- Red Hat: 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-2026-111817; each belongs to its advisory, not to every product listed. How records are collected and checked.
How do I fix CVE-2026-111817?
Upgrade to a fixed release named by the vendor:
- Apache: 10.1.5, 10.2.1
- Red Hat: 10.1.5, 10.2.1
- Users are recommended to upgrade to version 10.1.5 or 10.2.1, which fix the issue. (Apache)
- Disable proxy.config.http.drop_chunked_trailers on 8.1.11/9.2.x (off by default there; affected only if enabled); on 10.x, where the setting is on by default, upgrade to the fixed versions 10.1.5/10.2.1. (Red Hat)
Vendor advisories for CVE-2026-111817
Apache
1 advisory- Advisory severityMedium6.9
Medium [CVE-2026-111817] Apache Traffic Server can stall a chunked transfer that it passes through with its trailers removed (proxy.config.http.drop_chunked_trailers) until the connection times out, because it waits for the trailer bytes it has already dropped
CVE-2026-111817Source published Source updated
Apache Traffic Server can stall a chunked transfer that it passes through with its trailers removed (proxy.config.http.drop_chunked_trailers) until the connection times out, because it waits for the trailer bytes it has already dropped. Trailer dropping is on by default in 10.x. In 8.1.11 and 9.2.x it is off by default, and those versions are affected only if it is enabled. This issue affects Apache Traffic Server: 8.1.11, from 9.2.5 through 9.2.15, from 10.0.0 through 10.1.4, 10.2.0. Users are recommended to upgrade to version 10.1.5 or 10.2.1, which fix the issue.
- Affected products in this advisory
- Apache Traffic Server
- Source-reported affected versions
- 9.2.5 through 9.2.15
- 10.0.0 through 10.1.4
- Source-reported fixed versions
- 10.1.5
- 10.2.1
- Mitigation guidance
- Users are recommended to upgrade to version 10.1.5 or 10.2.1, which fix the issue.
Red Hat
1 advisory- Advisory severityMedium5.3
Medium [CVE-2026-111817] Denial of Service via dropped chunked trailers
CVE-2026-111817Source published Source updated
Denial of Service via dropped chunked trailers. Red Hat rates this moderate (CVSS 5.3). Weakness: CWE-444.
- Related products — impact not confirmed
- No product details extracted. Check the source bulletin.
- Source-reported affected versions
- 8.1.11
- 9.2.5
- 9.2.15
- 10.0.0
2 more entries in the full advisory.
- Source-reported fixed versions
- 10.1.5
- 10.2.1
- Mitigation guidance
- Disable proxy.config.http.drop_chunked_trailers on 8.1.11/9.2.x (off by default there; affected only if enabled); on 10.x, where the setting is on by default, upgrade to the fixed versions 10.1.5/10.2.1.
References
More Apache advisories
CVE-2026-112381Oct 21, 2026Apache Traffic Server can crash with a null pointer dereferenceCVE-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 lineCVE-2026-111815Oct 21, 2026Apache Traffic Server can resume a TLS session across SNI virtual hosts
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