CVE-2026-42013
Gnutls: gnutls: certificate validation bypass due to oversized subject alternative name
No known exploitation. EPSS puts it in the 44th percentile. No fix published yet.
What to do
No fixed build or workaround is published yet. Limit exposure and watch for a patch.
What it is
From the CVE record
A flaw was found in gnutls. When validating certificates, an oversized Subject Alternative Name (SAN) could cause the validation process to incorrectly fall back to checking the Common Name (CN) field. This could allow a remote attacker to bypass proper certificate validation, potentially leading to spoofing or man-in-the-middle attacks.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.6% chance of exploitation activity in the next 30 days, which ranks it in the 44th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
17 events over 100 days, from the signal feeds we watch.
- Record updated
- Record updatedrecord updated
- Record updated
- Record updated
- Record updated
- Record updated
Affected products
- Red Hat Enterprise Linux 10Operating Systems / linux-distro
- Red Hat Enterprise Linux 10.0 Extended Update SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 7 Extended Lifecycle SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-OnOperating Systems / linux-distro
- Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update SupportOperating Systems / linux-distro
- Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-OnOperating Systems / linux-distro
- Red Hat Enterprise Linux 8.8 Telecommunications Update ServiceOperating Systems / linux-distro
And 17 more affected products. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N
Scored 8.2 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity LowNo special conditions — the attack can be reliably reproduced
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality LowSome restricted information is disclosed, but limited in scope
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability NoneNo availability impact
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
Sources
References in the record
- access.redhat.com/errata/RHSA-2026:13274
- access.redhat.com/errata/RHSA-2026:20611
- access.redhat.com/errata/RHSA-2026:20612
And 20 more references. See all after sign-in
Watch the software you run.
My Stack ranks new CVEs for your products by real-world exploitation, so the next serious one reaches you without reading every advisory.
We'll flag the next CVE, public exploit or patch for Red Hat, not every advisory.
A free account adds
- The full version matrix and every affected product
- Exploit links, proofs of concept and Metasploit modules
- Email alerts for the products you watch
- The same data over REST API, MCP and CLI