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Libsoup CVE-2026-3099

MEDIUM
Reusing a Nonce, Key Pair in Encryption (CWE-323)
2026-03-12 secalert@redhat.com
Authentication Bypass Red Hat Enterprise Linux Suse Libsoup Gnome
5.8
CVSS 3.1 · NVD
View

Vulnerability Assessment

Weakness
CWE
CWE-323
OWASP Top 10:2025
A04:2025 - Cryptographic Failures
ASVS 5.0
V11 - Cryptography Nonce/key pair uniqueness
Impact

CVSS 5.8 (MEDIUM). Attack vector: Network. Complexity: High. Privileges required: None. User interaction: Required. Exploitation no authentication required. Exploitable via remote/network.
Exploit ScenarioDerived

A remote attacker without authentication could exploit this vulnerability to compromise the affected system.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Libsoup's digest authentication mechanism fails to validate nonce reuse and enforce proper nonce-count incrementation, enabling attackers to replay captured authentication headers to bypass access controls. A remote attacker can exploit this to impersonate legitimate users and access protected resources without valid credentials. No patch is currently available.

Earlier versions of this analysis (1)
v1 Mar 12, 2026 - 19:57 CVSS 5.8

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. [CVSS 5.8 MEDIUM]

RemediationAI

Monitor vendor advisories for a patch. Restrict network access to the affected service where possible.

Affects your stack

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Technical ContextAI · show details

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.

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  • Exploit and PoC references, threat intelligence from 22 sources
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Severity by source

NVD PRIMARY 5.8 MEDIUM
AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:L
SUSE MEDIUM
Red Hat 5.8 MEDIUM

Primary rating from NVD.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
Low

DescriptionCVE.org

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.

Executive ViewAI

Why It Matters

Organizations using A flaw should be aware of moderate risk from CVE-2026-3099 rated CVSS 5.8. Exploitation could compromise the security of affected deployments. Organizations should apply vendor updates when available and monitor for exploitation.

Business Impact: Low
Compensating Controls

Apply vendor patch. If patching is delayed: restrict network access and enable monitoring.

Threat Intelligence Overview

EPSS Score
0.1%
Top 71% exploitable
Data Quality
5 sources
Confidence: Medium
NVD CVE.org EPSS MSRC Vendor VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Low

Priority Score

29
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +29
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication Bypass CRITICAL

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

Affected Products (CPE)CVE.org

cpe:2.3:a:gnome:libsoup:-:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:6.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*

More in Libsoup

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CVE-2019-17266 CRITICAL POC
9.8 Oct 06

libsoup from versions 2.65.1 until 2.68.1 have a heap-based buffer over-read because soup_ntlm_parse_challenge() in soup
CVE-2024-52530 HIGH POC
7.5 Nov 11

GNOME libsoup before 3.6.0 allows HTTP request smuggling in some configurations because '\0' characters at the end of he
CVE-2025-2784 MEDIUM POC
6.5 Apr 03

A flaw was found in libsoup. Rated high severity (CVSS 7.0), this vulnerability is remotely exploitable, no authenticati
CVE-2024-52531 MEDIUM POC
6.5 Nov 11

GNOME libsoup before 3.6.1 allows a buffer overflow in applications that perform conversion to UTF-8 in soup_header_pars
CVE-2026-102560 CRITICAL
9.8 Sep 29

A heap buffer overflow exists in libsoup's WebSocket permessage-deflate compression path: when a very large outbound mes
CVE-2026-1536 MEDIUM POC
5.8 Jan 28

HTTP header injection in libsoup through CRLF sequences in the Content-Disposition header allows unauthenticated remote

CVE-2026-1467 MEDIUM POC
5.8 Jan 27

libsoup's improper handling of URL-decoded input in HTTP proxy configurations allows remote attackers to inject CRLF seq
CVE-2018-12910 CRITICAL
9.8 Jul 05

The get_cookies function in soup-cookie-jar.c in libsoup 2.63.2 allows attackers to have unspecified impact via an empty
CVE-2026-102559 HIGH
8.6 Sep 29

Heap memory corruption in libsoup can be triggered when a WebSocket client using libsoup constructs a masked outgoing fr
CVE-2026-102558 HIGH
8.6 Sep 29

Heap out-of-bounds read in libsoup's WebSocket implementation allows a remote, unauthenticated peer to trigger a heap bu
CVE-2026-102557 HIGH
8.6 Sep 29

Heap corruption and denial of service in libsoup stem from unbounded WebSocket message reassembly: the code accumulates

CVE-2026-102556 HIGH
8.6 Sep 29

A type-confusion memory-safety flaw in libsoup's WebSocket handling can crash or corrupt the heap of applications that p

Same weakness CWE-323 – Reusing a Nonce, Key Pair in Encryption

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8.1
CVE-2025-46632 MEDIUM POC
6.5
CVE-2023-28997 MEDIUM POC
6.5
CVE-2017-7902 CRITICAL
9.8
CVE-2026-12205 CRITICAL
9.1
CVE-2025-64767 CRITICAL
9.1

Same technique Authentication Bypass

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CVE-2015-3306 CRITICAL POC
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CVE-2023-22515 CRITICAL POC
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CVE-2012-4681 CRITICAL POC
9.8
CVE-2013-2465 CRITICAL POC
9.8
CVE-2011-3544 CRITICAL POC
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CVE-2022-40684 CRITICAL POC
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CVE-2025-61882 CRITICAL POC
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CVE-2024-0012 CRITICAL POC
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Vendor StatusVendor

SUSE

Severity: Medium
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Micro 5.2 Fixed

References

Advisories & patches
ADVISORY https://vuldb.com/?id.350660 REF https://access.redhat.com/security/cve/CVE-2026-3099 REF https://bugzilla.redhat.com/show_bug.cgi?id=2442232 REF https://gitlab.gnome.org/GNOME/libsoup/-/issues/495

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