CVE-2013-6401: Jansson, possibly 2.4 and earlier, does not restrict the ability to trigger hash collisions predictably, which

Q: How do I fix CVE-2013-6401?

jansson: upgrade to newer than 2.4. Exact commands for each OS are on this page.

Q: Is CVE-2013-6401 being exploited?

CVE-2013-6401 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2013-6401 affect?

CVE-2013-6401 affects jansson. Severity is medium (CVSS 5.0). Jansson, possibly 2.4 and earlier, does not restrict the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted JSON document.

Q: How urgent is CVE-2013-6401?

Priority 38/100. No elevated risk signals yet.

Routine

MEDIUM 5.0UPGRADE

CVE-2013-6401 is a medium-severity flaw (CVSS 5.0) affecting jansson. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Jansson, possibly 2.4 and earlier, does not restrict the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted JSON document.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.0 (Medium)
EPSS exploit chance	2.0% (top 19%)
CISA exploited list	No
Weakness	CWE-310
Published	2014-03-21
Last modified	2026-06-17

Publisher (CNA): Red Hat, Inc. · Vendor: jansson project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2014-03-21 01:04 UTCPublished CVE record published
2026-06-17 00:00 UTCUpdated Record last modified

jansson project jansson UPGRADE

Affected: <= 2.4 · 2.0 · 2.0.1 · 2.1 · 2.2 · 2.2.1 · 2.3 · 2.3.1

Fixed in: newer than 2.4

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 2.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade jansson

Note

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

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-2013-6401?

jansson: upgrade to newer than 2.4. Exact commands for each OS are on this page.

Is CVE-2013-6401 being exploited?

CVE-2013-6401 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-2013-6401 affect?

CVE-2013-6401 affects jansson. Severity is medium (CVSS 5.0). Jansson, possibly 2.4 and earlier, does not restrict the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted JSON document.

How urgent is CVE-2013-6401?

Priority 38/100. No elevated risk signals yet.

Related CVEs

CVE-2020-36325 HIGH 7.5 UPGRADE An issue was discovered in Jansson through 2.13.1
CVE-2016-4425 MEDIUM 6.5 UPGRADE Jansson 2.7 and earlier allows context-dependent attackers to cause a denial of service (deep recursion, stack

References

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