What is CVE-2012-5821?

CVE-2012-5821 is a medium-severity vulnerability in Lynx, classified under Improper Certificate Validation. CVSS score: 5.9/10. Published 2012-11-04.

How severe is CVE-2012-5821?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Vulnerability in Lynx

CVE-2012-5821

Lynx does not verify that the server's certificate is signed by a trusted certification authority, which allows man-in-the-middle attackers to spoof SSL servers via a crafted certificate, related to improper use of a certain GnuTLS function.

Vulnerability class: Improper Certificate Validation

Published 2012-11-04 · last modified 2026-06-16.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N.

EPSS exploit prediction

EPSS: 0.008 (55.5th percentile), scored 2026-10-06.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000

Affected products

Lynx
Canonical Ubuntu Linux — versions 10.04, 11.10, 12.04

Weakness classification (CWE)

CWE-295 — Improper Certificate Validation

References

wiki.mageia.org/en/Support/Advisories/MGASA-2012-0351 (Third Party Advisory)
www.ubuntu.com/usn/USN-1642-1 (vendor-advisory, Third Party Advisory)
exchange.xforce.ibmcloud.com/vulnerabilities/79930 (VDB Entry, Third Party Advisory, vdb-entry)
www.mandriva.com/security/advisories (vendor-advisory, Broken Link)
www.cs.utexas.edu/~shmat/shmat_ccs12.pdf (Exploit)

Frequently asked questions

What is CVE-2012-5821?: CVE-2012-5821 is a medium-severity vulnerability in Lynx, classified under Improper Certificate Validation. CVSS score: 5.9/10. Published 2012-11-04.
How severe is CVE-2012-5821?: Medium severity. CVSS v3 base score is 5.9 out of 10.