What’s Vulnerable › Vulnerabilities

CVE-2026-3099: Libsoup: libsoup: authentication bypass via digest authentication replay attack

• Severity: high (CVSS 7.3 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-03-12 · updated 2026-06-17
• Weakness: CWE-323

Description

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 authentication header and replay it repeatedly. Consequently, the attacker can bypass authentication and gain unauthorized access to protected resources, impersonating the legitimate user.

Affected products

• GNOME libsoup: all versions
• Red Hat Enterprise Linux: 6.0, 7.0, 8.0, 9.0, 10.0

References

• https://access.redhat.com/security/cve/CVE-2026-3099
• https://bugzilla.redhat.com/show_bug.cgi?id=2442232
• https://gitlab.gnome.org/GNOME/libsoup/-/issues/495

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