# CVE-2026-33845: GnuTLS integer underflow in DTLS handshake parsing

Source: https://junglewise.ai/threats/cve-2026-33845-gnutls-integer-underflow-in-dtls-handshake-parsing  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-04-30. Updated: 2026-05-27  
License: CC BY 4.0 with a link back

CVE-2026-33845 · Severity: high · CVSS 7.5 · Published 2026-04-30

GnuTLS is a widely used security library that enables encrypted communications for various applications and operating systems. A vulnerability in how it handles specific network handshake messages could allow a remote attacker to crash services using the library. This could lead to a denial of service, impacting the availability of secure web services and corporate infrastructure.

Technologies: [Gnutls](https://junglewise.ai/threats/technologies/gnutls). Vendors: [Gnu](https://junglewise.ai/threats/vendors/gnu).

## Quick answers

**Is CVE-2026-33845 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-33845 being exploited in the wild.

**How severe is CVE-2026-33845?** High severity, with a CVSS score of 7.5, published 30 April 2026.

**Which products and versions are affected?** Gnutls versions prior to 3.8.13-1.hum1.

**Is there a fix for CVE-2026-33845?** A patch was published on 2026-05-02: Red Hat released initial security advisory RHSA-2026:13274 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-33845 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-33845?** Check whether you run Gnutls at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

An integer underflow vulnerability exists in GnuTLS during the reassembly of DTLS (Datagram Transport Layer Security) handshake fragments. The flaw is triggered when the library processes malformed fragments characterized by a zero length but a non-zero offset. This condition leads to an out-of-bounds read during the reassembly process. A remote, unauthenticated attacker can exploit this over the network by sending specially crafted DTLS packets. Successful exploitation can result in a denial of service (application crash) or potentially sensitive information disclosure from memory. Red Hat has released security updates (e.g., RHSA-2026:20611) to address this issue across its enterprise platforms.

## Affected products

- GNU GnuTLS versions prior to 3.8.13-1.hum1
- Red Hat Enterprise Linux 6.0, 7.0, 8.0, 9.0, 10.0
- Red Hat OpenShift Container Platform 4.0

## Timeline

- 2026-03-24: disclosed: Initial report in Red Hat Bugzilla
- 2026-04-30: advisory: NVD publication date
- 2026-05-02: patched: Red Hat released initial security advisory RHSA-2026:13274

## References

- [https://access.redhat.com/errata/RHSA-2026:13274](https://access.redhat.com/errata/RHSA-2026:13274)
- [https://access.redhat.com/errata/RHSA-2026:20611](https://access.redhat.com/errata/RHSA-2026:20611)
- [https://access.redhat.com/security/cve/CVE-2026-33845](https://access.redhat.com/security/cve/CVE-2026-33845)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2450624](https://bugzilla.redhat.com/show_bug.cgi?id=2450624)

## Related threats

- [GnuTLS hostname verification bypass via Common Name fallback](https://junglewise.ai/threats/cve-2026-88647-a-hostname-verification-bypass-in-gnutls-v3-8-13-allows-attackers)
- [GnuTLS NULL pointer dereference in PSK binder verification](https://junglewise.ai/threats/cve-2026-1584-gnutls-null-pointer-dereference-in-psk-binder-verification)
- [GnuTLS heap buffer overread in SCT extension parsing](https://junglewise.ai/threats/cve-2025-32989-gnutls-heap-buffer-overread-in-sct-extension-parsing)