CVE-2026-33307: Mod_gnutls is a TLS module for Apache HTTPD based on GnuTLS

Q: How do I fix CVE-2026-33307?

mod gnutls: upgrade to 0.12.3. Exact commands for each OS are on this page.

Q: Is CVE-2026-33307 being exploited?

CVE-2026-33307 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-2026-33307 affect?

CVE-2026-33307 affects mod gnutls. Severity is high (CVSS 7.5). Mod_gnutls is a TLS module for Apache HTTPD based on GnuTLS. In versions prior to 0.12.3 and 0.13.0, code for client certificate verification imported the certificate chain sent by the client into a fixed size `gnutls_x509_crt_t x509[]` arr

Q: How urgent is CVE-2026-33307?

Priority 43/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADE

CVE-2026-33307 is a high-severity flaw (CVSS 7.5) affecting mod gnutls. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Mod_gnutls is a TLS module for Apache HTTPD based on GnuTLS. In versions prior to 0.12.3 and 0.13.0, code for client certificate verification imported the certificate chain sent by the client into a fixed size `gnutls_x509_crt_t x509[]` array without checking the number of certificates is less than or equal to the array size. `gnutls_x509_crt_t` is a `typedef` for a pointer to an opaque GnuTLS structure created using with `gnutls_x509_crt_init()`

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 72%)
CISA exploited list	No
Weakness	CWE-121
Published	2026-03-24
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: mod gnutls project

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

Am I affected?

Timeline

2026-03-24 02:16 UTCPublished CVE record published
2026-06-17 10:37 UTCUpdated Record last modified

mod gnutls project mod gnutls UPGRADE

Affected: < 0.12.3

Fixed in: 0.12.3

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy mod-gnutls || rpm -q mod-gnutls || mod-gnutls --version

2. UPGRADE to 0.12.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mod-gnutls

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mod-gnutls

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-2026-33307?

mod gnutls: upgrade to 0.12.3. Exact commands for each OS are on this page.

Is CVE-2026-33307 being exploited?

CVE-2026-33307 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-2026-33307 affect?

CVE-2026-33307 affects mod gnutls. Severity is high (CVSS 7.5). Mod_gnutls is a TLS module for Apache HTTPD based on GnuTLS. In versions prior to 0.12.3 and 0.13.0, code for client certificate verification imported the certificate chain sent by the client into a fixed size `gnutls_x509_crt_t x509[]` arr

How urgent is CVE-2026-33307?

Priority 43/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Apache HTTP Server vulnerabilities · GnuTLS vulnerabilities

Related CVEs

CVE-2026-33308 MEDIUM 6.8 UPGRADE Mod_gnutls is a TLS module for Apache HTTPD based on GnuTLS

References

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