Session-data disclosure via predictable cookie IVs
Published Mar 31, 2026 · Updated Mar 31, 2026
Weak IV generation in PAGI::Middleware::Session::Store::Cookie 0.001003 and earlier allows remote attackers to read session data. The _random_bytes routine reads /dev/urandom directly and, on failure, fills the cookie-encryption IV with Perl rand output. The fallback is reached on systems without that device, including Windows; the reported impact is limited to session-data confidentiality.
Summary
What happened
Weak IV generation in PAGI::Middleware::Session::Store::Cookie 0.001003 and earlier allows remote attackers to read session data. The _random_bytes routine reads /dev/urandom directly and, on failure, fills the cookie-encryption IV with Perl rand output. The fallback is reached on systems without that device, including Windows; the reported impact is limited to session-data confidentiality.
The record
- CVE
- CVE-2026-5087
- Published
- Mar 31, 2026
- Updated
- Mar 31, 2026
- Vendor
- John Napiorkowski
- Product
- PAGI::Middleware::Session::Store::Cookie
- Classifications
- CWE-338, CWE-1204, T1550.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 31, 2026CVE publishedPublication date reported by the CVE source.
- Mar 31, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <=0.001003
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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