CVE-2025-9820: Red Hat Enterprise Linux 10 · Stack-based Buffer Overflow
Affects Red Hat Enterprise Linux 10Source CVE Database V5
Not known to be exploited · CVSS 4.0 Medium : upgrade to 10.2 when convenient.
Data as of 25 Oct 2026, 19:02 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 12% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 10.2
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LExploitation evidence
Disclosed: evidence found.
CVE published 26 Jan 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 2026-10-25.
What to do
Upgrade redhat/gnutls to 10.2.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Red HatRed Hat Enterprise Linux 10 | Affected– | Fixed in– |
| Red HatRed Hat Enterprise Linux 8 | Affected– | Fixed in– |
| Red HatRed Hat Enterprise Linux 9 | Affected– | Fixed in– |
| Red HatRHEL-8 based Middleware Containers | Affected– | Fixed in– |
| Red HatRHEL-8 based Middleware Containers | Affected– | Fixed in– |
| Red HatRHEL-8 based Middleware Containers | Affected– | Fixed in– |
| Red HatRHEL-8 based Middleware Containers | Affected– | Fixed in– |
| Red HatRHEL-8 based Middleware Containers | Affected– | Fixed in– |
| Red HatRHEL-8 based Middleware Containers | Affected– | Fixed in– |
| Red HatRHEL-8 based Middleware Containers | Affected– | Fixed in– |
| Red HatCert Manager support for Red Hat OpenShift release 1.18 | Affected– | Fixed in– |
| Red HatCert Manager support for Red Hat OpenShift release 1.18 | Affected– | Fixed in– |
| Red HatCert Manager support for Red Hat OpenShift release 1.18 | Affected– | Fixed in– |
| Red HatCert Manager support for Red Hat OpenShift release 1.18 | Affected– | Fixed in– |
| Red HatCert Manager support for Red Hat OpenShift release 1.18 | Affected– | Fixed in– |
| Red HatRed Hat Ceph Storage 8 | Affected– | Fixed in– |
| Red HatRed Hat Discovery 2 | Affected– | Fixed in– |
| Red HatRed Hat Discovery 2 | Affected– | Fixed in– |
| Red HatRed Hat Hardened Images | Affected– | Fixed in– |
| Red HatRed Hat Insights proxy 1.5 | Affected– | Fixed in– |
| Red HatRed Hat Update Infrastructure 5 | Affected– | Fixed in– |
| Red HatRed Hat Update Infrastructure 5 | Affected– | Fixed in– |
| Red HatRed Hat Update Infrastructure 5 | Affected– | Fixed in– |
| Red HatRed Hat Update Infrastructure 5 | Affected– | Fixed in– |
| Red HatRed Hat Enterprise Linux 6 | Affected– | Fixed in– |
| Red HatRed Hat Enterprise Linux 7 | Affected– | Fixed in– |
| Red HatRed Hat OpenShift Container Platform 4 | Affected– | Fixed in– |
Red Hatredhat/gnutlspkg:rpm/redhat/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
Red Hat has released official security updates for GnuTLS in Red Hat Enterprise Linux 10 that fix this vulnerability. Users should upgrade to the patched GnuTLS packages (e.g., gnutls-3.8.10-3.el10_1 or later) as provided in advisories RHSA-2026:3477 and RHSA-2026:13812. Applying these updates fully mitigates the vulnerability. No additional mitigation steps are required beyond applying the vendor-provided patches.
Description
A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.
References
- access.redhat.com/errata/RHSA-2026:13812 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:3477 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:4188 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:4655 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:4943 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:5585 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:5606 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7329 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:7477 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2025-9820 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2392528 (opens in a new tab)
- gitlab.com/gnutls/gnutls/-/commit/1d56f96f6ab5034d677136b9d50b5a75dff0faf5 (opens in a new tab)
- gitlab.com/gnutls/gnutls/-/issues/1732 (opens in a new tab)
- gnutls.org/security-new.html (opens in a new tab)
- openwall.com/lists/oss-security/2025/11/20/2 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-032379.html (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:82347 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:82354 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:82372 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:82857 (opens in a new tab)