# CVE-2026-3255: HTTP::Session2 versions before 1.12 for Perl may generate weak session ids using the rand() function

> Attackers can predict session IDs due to weak random number generation, potentially leading to account takeover.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 27 Feb 2026
- **Updated:** 3 Mar 2026
- **Also known as:** GHSA-2p7f-7xjf-8q9q

## What is CVE-2026-3255?

CVE-2026-3255 is a medium-severity vulnerability in TOKUHIROM HTTP::Session2, published on 27 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

HTTP::Session2 versions before 1.12 for Perl for Perl may generate weak session ids using the rand() function.

The HTTP::Session2 session id generator returns a SHA-1 hash seeded with the built-in rand function, the 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.

HTTP::Session2 after version 1.02 will attempt to use the /dev/urandom device to generate a session id, but if the device is unavailable (for example, under Windows), then it will revert to the insecure method described above.

Weakness: CWE-340 (Generation of Predictable Numbers or Identifiers), CWE-338 (Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG))

## Which versions are affected by CVE-2026-3255?

It affects 1 product.


Products: Tokuhirom Http\.

## How do I fix CVE-2026-3255?

No fix has been published for CVE-2026-3255 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-3255 being exploited?

There is no known exploitation of CVE-2026-3255 in the wild and no public exploit code.

## Other vulnerabilities in TOKUHIROM HTTP::Session2

- [CVE-2018-25160](https://insights.sbomify.com/CVE-2018-25160/): Code injection in HTTP::Session2 (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-3255 and fix it if it is affected.

What it is: CVE-2026-3255 is a medium-severity vulnerability in TOKUHIROM HTTP::Session2, published on 27 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-3255 in the wild and no public exploit code.

Affected product: TOKUHIROM HTTP::Session2. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-3255/ (Markdown: https://insights.sbomify.com/CVE-2026-3255/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-3255
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-3255
- OSV: https://osv.dev/vulnerability/CVE-2026-3255

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-3255/
Summaries are generated and may contain mistakes; the official description above is the record.