🛡️ CVE-2026-56016 on Ubuntu — libcgi-session-perl

⚪ Unknown ✅ No Known Exploit OSV

N/A

CVSS Score

0 Low4 Medium7 High9 Critical10

Description

CGI::Session::ID::md5 versions before 4.49 for Perl generate predictable session ids from low-entropy sources. The generate_id method builds the session id from a MD5 digest of the process id, the epoch time, and the built-in rand() function. All three are predictable, low-entropy sources: the PID is drawn from a small range, the epoch time can be guessed or read from the HTTP Date header, and Perl's rand() is unsuitable for security purposes because it is predictable and reversible. An attacker who predicts a session id can impersonate the corresponding session and bypass authentication.

Distribution advisory

This page covers CVE-2026-56016 as tracked by Ubuntu, for the package libcgi-session-perl. No fixed version has been recorded for this distribution yet.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability none.

Weakness class

UBUNTU-CVE-2026-56016 is classified as CWE-338: Use of Cryptographically Weak PRNG. A general-purpose random number generator is used where a cryptographic one is required.

Affected software

UBUNTU-CVE-2026-56016 is recorded against 1 package.

libcgi-session-perl

Timeline and source

Published on 1 July 2026 and last revised on 2 July 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

ubuntu.com (Report)
www.cve.org (Report)
lists.security.metacpan.org (Report)
metacpan.org (Report)
metacpan.org (Report)

Details

Severity Unknown

CVSS Score N/A

CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CWE N/A

Public Exploit ✅ No

Source OSV

Published 2026-07-01

Updated 2026-08-11

Modified 2026-07-02

Fix URL N/A

Affected Packages

Software	From version	Fixed in
libcgi-session-perl	—	—

References

REPORT https://ubuntu.com/security/CVE-2026-56016

REPORT https://www.cve.org/CVERecord?id=CVE-2026-56016

REPORT https://lists.security.metacpan.org/cve-announce/msg/41439279/

REPORT https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/changes

REPORT https://metacpan.org/release/MARKSTOS/CGI-Session-4.49/source/lib/CGI/Session/ID/md5.pm

🔗 NVD 🔗 Mitre

Similar Threats

Unknown DEBIAN-CVE-2026-56016

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