USN-8571-2: Apache HTTP Server regression
Ubuntu issues USN-8571-2 fixing an Apache HTTP Server regression that prevented startup when HTTP/2 proxying was enabled.
Ubuntu released USN-8571-2 to fix a regression introduced by USN-8571-1 in Apache HTTP Server. The earlier fix was incomplete due to a missing library symbol, causing Apache to fail to start when HTTP/2 proxying was enabled. The original advisory addressed CVE-2026-33007, a memory-handling flaw in mod_authn_socache allowing remote denial of service, and an HTTP response splitting vulnerability affecting multiple modules, credited to Pavel Kohout, Arkadi Vainbrand, Haruki Oyama, Merih Mengisteab, and Dawit Jeong.
- USN-8571-2 fixes Apache startup failure with HTTP/2 proxying enabled
- Regression stemmed from a missing library symbol in USN-8571-1
- Underlying issues include CVE-2026-33007 DoS in mod_authn_socache
- HTTP response splitting flaw was fixed in multiple Apache modules
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-33007 | A NULL pointer dereference in the mod_authn_socache in Apache HTTP Server 2.4.66 and earlier allows an unauthenticated remote user to crash a child process in a A NULL pointer dereference in the mod_authn_socache in Apache HTTP Server 2.4.66 and earlier allows an unauthenticated remote user to crash a child process in a caching forward proxy configuration. Users are recommended to upgrade to version 2.4.67, which fixes this issue. NVD description · AI analysis pending | 5.3 | <1% |
| — |
USN-8571-1 fixed vulnerabilities in Apache HTTP Server. That fix was incomplete due to a missing library symbol, resulting in a regression that could cause Apache HTTP Server to fail to start when HTTP/2 proxying was enabled. This update fixes the problem. We apologize for the inconvenience. Original advisory details: Pavel Kohout and Arkadi Vainbrand discovered that Apache HTTP Server incorrectly handled certain memory operations in mod_authn_socache. A remote attacker could possibly use this issue to cause a denial of service. (CVE-2026-33007) Haruki Oyama, Merih Mengisteab, and Dawit Jeong discovered that Apache HTTP Server had an HTTP response splitting vulnerability in multiple modules…
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