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

Routine

MEDIUM 5.3REMOTEUPGRADE

CVE-2026-8463 is a medium-severity flaw (CVSS 5.3) affecting crypt\. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 ar

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 74%)
CISA exploited list	No
Weakness	CWE-126, CWE-191
Published	2026-05-13
Last modified	2026-10-26

Publisher (CNA): CPANSec · Vendor: leont

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-13 14:18 UTCPublished CVE record published
2026-10-26 14:10 UTCUpdated Record last modified

leont crypt\ UPGRADE

Affected: >= 0.017 and < 0.031

Fixed in: 0.031

Safe to downgrade to: a release before 0.017

1. Check installed version

apt-cache policy crypt || rpm -q crypt || crypt --version

2. UPGRADE to 0.031 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade crypt

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade crypt

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.017 (Debian / Ubuntu)

apt-cache madison crypt sudo apt install crypt=<VERSION_BEFORE_0.017> sudo apt-mark hold crypt

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list crypt sudo dnf downgrade crypt-<VERSION_BEFORE_0.017> sudo dnf versionlock add crypt

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-8463?

crypt\: upgrade to 0.031. Exact commands for each OS are on this page.

Is CVE-2026-8463 being exploited?

CVE-2026-8463 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-8463 affect?

CVE-2026-8463 affects crypt\. Severity is medium (CVSS 5.3). 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 checki

How urgent is CVE-2026-8463?

Priority 30/100. Remotely exploitable, no login, no user action

Software pages

Perl vulnerabilities

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References

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