# CVE-2026-8463: Integer overflow in Crypt::Argon2

> An attacker can cause a crash or leak heap memory by providing empty input to the argon2_verify function in the Crypt::Argon2 Perl library.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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:** Yes
- **Published:** 13 May 2026
- **Updated:** 13 May 2026
- **Also known as:** DEBIAN-CVE-2026-8463, GHSA-3p6c-7qjr-35x9, UBUNTU-CVE-2026-8463

## What is CVE-2026-8463?

CVE-2026-8463 is a medium-severity vulnerability in LEONT Crypt::Argon2, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Crypt::Argon2 versions from 0.017 before 0.031 for Perl perform a heap out-of-bounds read in argon2_verify on empty encoded input.

The auto-detect form of argon2_verify passes encoded_len - 1 as the length argument to memchr without checking that encoded_len is non-zero. When the encoded string is empty, the size_t subtraction underflows to SIZE_MAX and memchr scans adjacent heap memory looking for a '$' separator byte.

A caller that invokes argon2_verify against a stored hash that may legitimately be empty (for example a placeholder row or a NULL column materialised as an empty string) reads out-of-bounds heap memory, which can crash the process or leak the position of an adjacent '$' byte into subsequent parsing.

Weakness: CWE-191 (Integer Underflow (Wrap or Wraparound)), CWE-126 (Buffer Over-read)

## Which versions are affected by CVE-2026-8463?

It affects 1 product.


Products: Leont Crypt\.

## How do I fix CVE-2026-8463?

Upgrade to a fixed version.

## Is CVE-2026-8463 being exploited?

There is no known exploitation of CVE-2026-8463 in the wild and no public exploit code.

## Other vulnerabilities in LEONT Crypt::Argon2

- [CVE-2026-2597](https://insights.sbomify.com/CVE-2026-2597/): Integer overflow in Crypt::SysRandom::XS (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-8463 and fix it if it is affected.

What it is: CVE-2026-8463 is a medium-severity vulnerability in LEONT Crypt::Argon2, published on 13 May 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-2026-8463 in the wild and no public exploit code.

Affected product: LEONT Crypt::Argon2. 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-2026-8463/ (Markdown: https://insights.sbomify.com/CVE-2026-8463/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-8463
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-8463
- OSV: https://osv.dev/vulnerability/CVE-2026-8463

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-8463/
Summaries are generated and may contain mistakes; the official description above is the record.