dbcve.org
Http\Application · Ktat

CVE-2026-3256

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-28
Fix available
A fix is available. Upgrade to after 0.53 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
HTTP::Session versions before 0.54 for Perl defaults to using insecurely generated session ids. HTTP::Session defaults to using HTTP::Session::ID::SHA1 to generate session ids using a SHA-1 hash seeded with the built-in rand function, the high resolution epoch time, and the PID. The PID will come from a small set of numbers, and the epoch time may be guessed, if it is not leaked from the HTTP Date header. The built-in rand function is unsuitable for cryptographic usage. The distribution includes HTTP::session::ID::MD5 which contains a similar flaw, but uses the MD5 hash instead.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The HTTP::Session Perl module versions before 0.54 uses a cryptographically weak session ID generator (HTTP::Session::ID::SHA1) that combines the insecure built-in rand() function with guessable values (PID from a small namespace and epoch time potentially leaked from HTTP headers). An attacker can predict or brute-force valid session IDs, enabling session hijacking attacks. An alternative ID generator using MD5 has the same flaw.

MitigationUpgrade HTTP::Session to version 0.54 or later, which uses cryptographically secure random generation for session IDs. If unable to upgrade immediately, audit applications for session ID exposure in headers like HTTP Date.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Http\Application
Affected:<= 0.53

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if HTTP::Session Perl module is installed
    Run 'perl -MHTTP::Session -e "print $HTTP::Session::VERSION"' or check via 'cpan -D HTTP::Session' or 'cpanm --info HTTP::Session'
    Affected if The module is not installed or the command fails, indicating HTTP::Session is not in use
  2. Determine installed version of HTTP::Session
    Execute 'perl -MHTTP::Session -e "print $HTTP::Session::VERSION"' to obtain the version number, or inspect the version in your project's dependency file (cpanfile, Makefile.PL, or similar)
    Affected if Version is 0.53 or lower, meaning the vulnerable version is present
  3. Verify application uses HTTP::Session for session management
    Search source code for 'use HTTP::Session' or 'HTTP::Session->new' statements in your application Perl files
    Affected if The application imports and uses HTTP::Session to manage sessions, enabling the flaw
  4. Inspect session ID generation method
    If accessible, examine the session ID creation code in the application or HTTP::Session source to confirm it relies on default SHA-1/MD5 hashing with weak rand() seeding
    Affected if Session IDs are generated using the default weak algorithm rather than cryptographically secure randomness

You are affected if HTTP::Session version 0.53 or earlier is installed and your application uses it for session management.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to a release after 0.53
Interim mitigation

Upgrade HTTP::Session to version 0.54 or later, which uses cryptographically secure random generation for session IDs. If unable to upgrade immediately, audit applications for session ID exposure in headers like HTTP Date.

Recommended fix High confidence

HTTP::Session 0.54

  1. Update HTTP::Session to version 0.54 or later using your Perl module manager (e.g., cpanm HTTP::Session or cpan HTTP::Session)
  2. Verify the installed version is 0.54 or higher by running 'perl -MHTTP::Session -e "print $HTTP::Session::VERSION"'
  3. If using a build system or dependency manager, update your cpanfile or similar to require HTTP::Session >= 0.54
  4. Regenerate any existing session IDs if applicable, as pre-0.54 IDs may have been generated with weak randomness

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Http\ Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,540
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,464.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-3256 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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