# CVE-2026-5419: GnuTLS non-constant-time PKCS#7 padding check

Source: https://junglewise.ai/threats/cve-2026-5419-gnutls-non-constant-time-pkcs-7-padding-check  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-01. Updated: 2026-06-01  
License: CC BY 4.0 with a link back

CVE-2026-5419 · Severity: low · CVSS 3.7 · Published 2026-06-01

GnuTLS is a widely used security library that helps applications establish secure, encrypted connections. A flaw was found where the library takes different amounts of time to process certain encrypted data, which could allow a remote attacker to slowly piece together sensitive information. While difficult to exploit, this could lead to the unauthorized disclosure of private data.

## Quick answers

**Is CVE-2026-5419 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-5419 being exploited in the wild.

**How severe is CVE-2026-5419?** Low severity, with a CVSS score of 3.7, published 1 June 2026.

**Which products and versions are affected?** GnuTLS gnutls 3.8.10-4.el10_2.

**Is there a fix for CVE-2026-5419?** A patch was published on 2026-05-26: Red Hat released security update RHSA-2026:20613 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-5419 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-5419?** Check whether anything you run is named in the advisory. 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

A timing side-channel vulnerability (CWE-208) exists in GnuTLS due to a non-constant-time PKCS#7 padding check during decryption. By observing minute differences in the time it takes for the library to respond to decryption requests with varying padding, a remote attacker can potentially perform a padding oracle-style attack to recover plaintext information. The attack requires a high degree of complexity and network stability to measure timing differences accurately. Red Hat has released patches for affected GnuTLS packages in RHEL 10.

## Affected products

- GnuTLS gnutls 3.8.10-4.el10_2

## Timeline

- 2026-05-26: patched: Red Hat released security update RHSA-2026:20613
- 2026-06-01: disclosed: CVE published in NVD dataset

## References

- [https://access.redhat.com/errata/RHSA-2026:20613](https://access.redhat.com/errata/RHSA-2026:20613)
- [https://access.redhat.com/security/cve/CVE-2026-5419](https://access.redhat.com/security/cve/CVE-2026-5419)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2467686](https://bugzilla.redhat.com/show_bug.cgi?id=2467686)