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VulnerabilityPublished

CVE-2026-56016: MARKSTOS CGI::Session::ID::md5 · Generation of Predictable Numbers or Identifiers

Affects MARKSTOS CGI::Session::ID::md5Source CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 4.49 when convenient.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
5.9Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.5% chance of exploitation in 30 days – higher than 44% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.49
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

What to do

Upgrade CGI::Session::ID::md5 and CGI-Session to 4.49.

Affected software

ProductAffectedFixed in
MARKSTOSCGI::Session::ID::md5Affected
  • <4.49
Fixed in
  • 4.49
GitHubCGI-Sessionpkg:github/CGI-SessionOther threatsAffected
  • <4.49
Fixed in
  • 4.49

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, users should avoid using CGI::Session::ID::md5 versions before 4.49 or implement additional session ID generation mechanisms that use cryptographically secure random sources. Avoid relying on Perl's built-in rand() for security-sensitive identifiers.

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.

References

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