CVE-2012-5821: Lynx does not verify that the server's certificate is signed by a trusted certification authority, which allow

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MEDIUM 5.9REMOTEWATCHLISTMITIGATEMITIGATE

CVE-2012-5821 is a medium-severity flaw (CVSS 5.9) affecting lynx, ubuntu linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Public exploit reference
Remotely exploitable, no login, no user action
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-295
Published	2012-11-04
Last modified	2026-06-16

Publisher (CNA): MITRE · Vendor: canonical · lynx

Last updated 2026-06-16 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2012-11-04 22:55 UTCPublished CVE record published
2026-06-16 23:47 UTCUpdated Record last modified

lynx lynx MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

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

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

canonical ubuntu linux MITIGATE

Affected: 10.04 · 11.10 · 12.04 · 12.10

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2012-5821?

lynx: mitigate or apply the listed mitigation; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2012-5821 being exploited?

CVE-2012-5821 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-2012-5821 affect?

CVE-2012-5821 affects lynx, ubuntu linux. Severity is medium (CVSS 5.9). 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

How urgent is CVE-2012-5821?

Priority 50/100. Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Ubuntu vulnerabilities · GnuTLS vulnerabilities

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References

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