CVE-2026-5081
Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.30%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
Apache::Session::Generate::ModUniqueId versions from 1.54 through 1.94 for Perl session ids are insecure. Apache::Session::Generate::ModUniqueId (added in version 1.54) uses the value of the UNIQUE_ID environment variable for the session id. The UNIQUE_ID variable is set by the Apache mod_unique_id plugin, which generates unique ids for the request. The id is based on the IPv4 address, the process id, the epoch time, a 16-bit counter and a thread index, with no obfuscation. The server IP is often available to the public, and if not available, can be guessed from previous session ids being issued. The process ids may also be guessed from previous session ids. The timestamp is easily guessed (and leaked in the HTTP Date response header). The purpose of mod_unique_id is to assign a unique id to requests so that events can be correlated in different logs. The id is not designed, nor is it suitable for security purposes.
- CVSS 3.1
- 9.1 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
- EPSS
- 0.30% probability · 23th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-340, CWE-341
- Affected
- chorny/apache\
- Source
- 9b29abf9-4ab0-4765-b253-1875cd9b441e
References
- https://httpd.apache.org/docs/current/mod/mod_unique_id.htmlProduct
- https://metacpan.org/pod/Apache::Session::Generate::RandomProduct
- http://www.openwall.com/lists/oss-security/2026/05/06/6Mailing List, Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2026-5081
- https://bugzilla.redhat.com/show_bug.cgi?id=2467174
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5081.json
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.