GnuTLS · Hostname Verification Bypass
Source GCVE Database
Not known to be exploited · CVSS 6.5 Medium : upgrade to 3.8.13 when convenient.
Data as of 4 Nov 2026, 07:29 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 6.5 |
|---|
- Patch
- Available – fixed in 3.8.13
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 8 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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 3 Nov 2026.
What to do
Upgrade the Debian debian/gnutls package to 3.8.13.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Debiandebian/gnutlspkg:deb/debian/gnutlsOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, users should consider avoiding use of GnuTLS v3.8.13 in security-critical environments or apply additional network-level protections such as TLS interception detection.
Description
GnuTLS version 3.8.13 contains a vulnerability in its hostname verification process that allows attackers to bypass the Common Name fallback mechanism. This flaw enables an attacker to use a specially crafted certificate to intercept and eavesdrop on communications. The vulnerability has a high severity with a CVSS score of 9.1, indicating critical impact on confidentiality and integrity without requiring user interaction or privileges.
References
- nvd.nist.gov/vuln/detail/CVE-2026-88647 (opens in a new tab)
- gist.github.com/lkloliver/f98ec3de1a871fdfc02b70b8b9ba7642 (opens in a new tab)
- github.com/lkloliver/poc/tree/main/CVE-2026-88647 (opens in a new tab)
- gitlab.com/gnutls/gnutls/-/blob/e2169a87c7fb91935c2845088204b102baed4c5f/SECURITY.md (opens in a new tab)
- gitlab.com/gnutls/gnutls/-/issues/1802 (opens in a new tab)
- gitlab.com/gnutls/gnutls/-/work_items/1965 (opens in a new tab)