CVE-2026-3099
Redhat Enterprise Linux 10.0 … 9.0
Raw vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:LSummary
CVE-2026-3099 is a medium-severity Reusing a Nonce, Key Pair in Encryption (CWE-323) vulnerability in Redhat Enterprise Linux. Its CVSS base score is 5.8 (Medium).
Operationally, ranked at the 28th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-3099, published on 2026-03-12, is a vulnerability in Libsoup, specifically in the server-side digest authentication implementation of the SoupAuthDomainDigest class. The flaw results from the component not properly tracking issued nonces or enforcing the required incrementing nonce-count (nc) attribute, as defined in CWE-323. This affects Libsoup's handling of HTTP digest authentication on the server side.
A remote attacker with no privileges can exploit this vulnerability by capturing a single valid authentication header from a legitimate user and replaying it repeatedly. Successful exploitation bypasses authentication mechanisms, enabling unauthorized access to protected resources and allowing the attacker to impersonate the legitimate user. The attack requires network access, high complexity, and user interaction, with a CVSS v3.1 base score of 5.8 (AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L).
Mitigation guidance and patches are detailed in related advisories, including Red Hat's security bulletin at https://access.redhat.com/security/cve/CVE-2026-3099, Bugzilla entry https://bugzilla.redhat.com/show_bug.cgi?id=2442232, and GNOME's Libsoup GitLab issue at https://gitlab.gnome.org/GNOME/libsoup/-/issues/495.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-11573
Vulnerability Data
A flaw was found in Libsoup. The server-side digest authentication implementation in the SoupAuthDomainDigest class does not properly track issued nonces or enforce the required incrementing nonce-count (nc) attribute. This vulnerability allows a remote attacker to capture a single valid…
more
authentication header and replay it repeatedly. Consequently, the attacker can bypass authentication and gain unauthorized access to protected resources, impersonating the legitimate user.
- CWE(s)
Related Threats
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
—
V6.8.3V11.3.4
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover nonce reuse through static analysis, fuzzing, or known-answer tests.
Engineering principles include correct use of cryptographic primitives such as unique nonces per key.
Selecting and implementing appropriate cryptographic algorithms and modes reduces nonce-reuse exposure.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly prevent nonce/key reuse errors in cryptographic implementations.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Mandates proper cryptographic key and nonce management, directly preventing nonce/key-pair reuse.
Security testing can detect nonce reuse, yet the control addresses many other issues beyond this CWE.
Secure-coding rules can require unique nonces, but the control is broader than this single weakness.