CVE-2026-8463

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.

CVSS v3.1 Score

5.3

MEDIUM

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

EPSS — Exploit Prediction

0.0004

Probability of exploitation

0.13%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-126 CWE-126

CWE-191 CWE-191

Affected Products

Vendor	Product	Versions
leont	crypt\	0.017 — 0.031

References

Advisories & Patches

https://github.com/Leont/crypt-argon2/commit/92eac03ce63d541e0ead7ea5a89b9b67ce0c0e64.patch

Other References

https://metacpan.org/release/LEONT/Crypt-Argon2-0.031/changes http://www.openwall.com/lists/oss-security/2026/05/13/4

Frequently Asked Questions

What is CVE-2026-8463? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-8463? +

CVE-2026-8463 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0004, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-8463? +

CVE-2026-8463 affects products from leont, specifically: crypt\. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-8463? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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