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CVE-2026-88647VulnerabilityPublished Updated

Gnutls26: GnuTLS v3.8.13 can perhaps unexpectedly trust a certificate on the basis of Common Name when Subject

Affects gnutls26Source GCVE Database

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Authoritative record:CVE-2026-88647· Medium 6.5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 5 Nov 2026, 12:34 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.16.5
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 8 Oct 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

What to do

Affected software

ProductAffectedFixed in
Ubuntu 26.10gnutls28pkg:deb/ubuntu/gnutls28?arch=source&distro=stonkingOther threatsAffected
  • =3.8.12-2ubuntu1
  • =3.8.12-2ubuntu1.1
  • =3.8.13-1ubuntu1
Fixed in–
Ubuntu 26.04 LTSgnutls28pkg:deb/ubuntu/gnutls28?arch=source&distro=resoluteOther threatsAffected
  • 3.8.9-3ubuntu2 – 3.8.12-2ubuntu1.1
4 affected builds
Fixed in–
Ubuntu 24.04 LTSgnutls28pkg:deb/ubuntu/gnutls28?arch=source&distro=nobleOther threatsAffected
  • 3.8.1-4ubuntu1 – 3.8.3-1ubuntu1
12 affected builds
Fixed in–
Ubuntu Pro FIPS-updates 24.04 LTSgnutls28pkg:deb/ubuntu/gnutls28?arch=source&distro=fips-updates/nobleOther threatsAffected
  • 3.8.3-1.1ubuntu3.1+Fips1 – 3.8.3-1.1ubuntu3.6+Fips1.2
5 affected builds
Fixed in–
Ubuntu 22.04 LTSgnutls28pkg:deb/ubuntu/gnutls28?arch=source&distro=jammyOther threatsAffected
  • 3.7.1-5ubuntu1 – 3.7.3-4ubuntu1.9
14 affected builds
Fixed in–
Ubuntu Pro FIPS-preview 22.04 LTSgnutls28pkg:deb/ubuntu/gnutls28?arch=source&distro=fips-preview/jammyOther threatsAffected
  • =3.7.3-4ubuntu1.2+Fips1.1
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

GnuTLS v3.8.13 can perhaps unexpectedly trust a certificate on the basis of Common Name when Subject Alternative Name has an SRV otherName (1.3.6.1.5.5.7.8.7) whose value is an OCTET STRING. NOTE: the Supplier does not consider this an actionable security vulnerability because of its "threat model doesn't consider attacks only possible by modifying anything within the trust boundary (private keys, trusted certificate authorities and their issued certificates including intermediate CAs, etc.)" policy.

References

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