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Libgcrypt EUVDEUVD-2026-25193

| CVE-2026-41990 MEDIUM
Out-of-bounds Write (CWE-787)
2026-04-23 mitre GHSA-78pv-qq8x-94px
Buffer Overflow Memory Corruption Gnupg Libgcrypt
4.0
CVSS 3.1 · Vendor: mitre
View

Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Local access to system
  2. Delivery
    Invoke Dilithium signing with malicious parameters
  3. Exploit
    Trigger out-of-bounds write in static array
  4. Execution
    Corrupt adjacent memory
  5. Impact
    Forge signatures or crash service

Vulnerability Assessment

Weakness
CWE
CWE-787
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, write limits
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Exploitation requires local access to a system running Libgcrypt 1.12.0 or 1.12.1 with Dilithium signature functionality active. The vulnerability is triggered through specific Dilithium signing input parameters that cause the static array index to exceed bounds; the description does not specify exact parameter values, suggesting the condition depends on particular key sizes or message formats used in Dilithium operations. Non-privileged (PR:N) local users can trigger the vulnerability, but high complexity (AC:H) indicates that exploitation demands particular combinations of Dilithium parameters or environmental conditions that do not occur in all typical signing operations. Remote exploitation is not possible due to AV:L (local-only vector); Dilithium must be actively used by an application on the affected system.
Impact

CVSS 4.0 with local attack vector (AV:L), high complexity (AC:H), and non-privileged user requirement (PR:N) reflects a moderate real-world risk. The vulnerability requires local access and specific conditions to trigger (high complexity suggests non-trivial exploitation prerequisites), limiting exposure to local-only scenarios rather than remote compromise. The integrity (I:L) and availability (I:L) impacts indicate potential memory corruption and service disruption without confidentiality breach. EPSS probability is not provided in the input; however, the combination of AV:L and AC:H suggests lower exploitability likelihood compared to network-accessible vulnerabilities. KEV status (CISA active exploitation tracking) is not confirmed in the input data. The vulnerability's reliance on local access and high complexity substantially reduces priority compared to unauthenticated network vulnerabilities, despite the memory corruption severity.
Exploit ScenarioDerived

A local user on a system running Libgcrypt 1.12.0 or 1.12.1 crafts a Dilithium signature operation with specific parameters that trigger the out-of-bounds write in the static array during signing. This write corrupts adjacent heap or stack memory, potentially causing the cryptographic operation to return incorrect signatures (integrity violation) or crash the calling process (availability impact). A malicious local user could exploit this to forge signatures or disrupt services relying on Libgcrypt's cryptographic functions.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 23, 2026

Libgcrypt before version 1.12.2 contains a bounds-check vulnerability in Dilithium signing operations where writes to a static array lack proper bounds validation, potentially causing memory corruption and integrity loss. The vulnerability affects local attackers with non-privileged access on systems running vulnerable versions 1.12.0 and 1.12.1. While the vulnerability does not involve attacker-controlled data in the array writes themselves, the missing bounds check creates an integrity and availability risk through uncontrolled memory modification.

RemediationAI

Vendor-released patch: Libgcrypt 1.12.2 or later. Update the Libgcrypt library package immediately through your distribution's package manager (apt, yum, pacman, etc.) or download directly from https://dev.gnupg.org/. Rebuilding dependent applications (GnuPG, OpenSSL, or custom applications linked against Libgcrypt) may be necessary after the library upgrade. If immediate patching is not possible, restrict local system access to untrusted users and monitor for memory corruption errors in application logs; however, this does not eliminate the underlying risk and should be treated as temporary only. Verify successful patching by confirming Libgcrypt version with libgcrypt-config --version returns 1.12.2 or higher.

Affected VersionsENISA

Libgcrypt 1.12.0 <1.12.2

Affected Packages

euvd libgcrypt fix: 1.12.2

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Technical ContextAI · show details

Libgcrypt is the cryptographic library underlying GnuPG and other applications requiring cryptographic primitives. This vulnerability resides in the Dilithium signature algorithm implementation (NIST FIPS 204 post-quantum cryptography standard). The root cause is classified as CWE-787 (Out-of-bounds Write) - specifically, a static array used during Dilithium signing receives writes without validating that indices remain within allocated bounds. Although the vulnerability description notes that attacker-controlled data is not directly used in the array indexing, the lack of bounds enforcement means that legitimate code paths with certain input parameters can write beyond the array's boundaries, corrupting adjacent memory.

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Severity by source

Vendor (mitre) PRIMARY 4.0 MEDIUM
AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
SUSE 3.6 LOW
AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
Red Hat 3.3 LOW

Primary rating from Vendor (mitre).

CVSS VectorVendor: mitre

Attack Vector
Local
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

Lifecycle Timeline

3
Patch released
Apr 27, 2026 - 18:33 nvd
Patch available
Patch available
Apr 23, 2026 - 06:16 EUVD
CVE Published
Apr 23, 2026 - 04:39 nvd
MEDIUM 4.0

DescriptionCVE.org

Libgcrypt before 1.12.2 mishandles Dilithium signing. Writes to a static array lack a bounds check but do not use attacker-controlled data.

Threat Intelligence Overview

EPSS Score
0.0%
Top 98% exploitable
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment 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 0.0%
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
None
System Exposure· derived
Small
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

20
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +20
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Memory Corruption HIGH

Memory corruption occurs when a program writes data beyond the boundaries of allocated memory regions or accesses memory in unintended ways, violating the integrity of the process's address space.

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Same weakness CWE-787 – Out-of-bounds Write

View all
CVE-2015-3113 CRITICAL POC
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CVE-2011-2462 CRITICAL POC
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CVE-2012-1889 HIGH POC
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CVE-2010-3333 HIGH POC
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CVE-2014-1761 HIGH POC
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CVE-2009-3129 HIGH POC
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CVE-2021-1732 HIGH POC
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CVE-2013-3346 CRITICAL POC
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Same technique Buffer Overflow

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CVE-2017-7269 CRITICAL POC
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CVE-2015-5119 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
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CVE-2019-11043 CRITICAL POC
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CVE-2009-0927 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: Low
Product Status
SLES15-SP5-CHOST-BYOS-SAP-CCloud Fixed
SLES15-SP6-CHOST-BYOS Fixed
SLES15-SP6-CHOST-BYOS-Aliyun Fixed
SLES15-SP6-CHOST-BYOS-Azure Fixed
SLES15-SP6-CHOST-BYOS-EC2 Fixed

References

Advisories & patches
ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-41990 ADVISORY https://ubuntu.com/security/notices/USN-8319-1 ADVISORY https://vuldb.com/vuln/359120 REF https://dev.gnupg.org/T8208 REF https://lists.gnupg.org/pipermail/gnupg-announce/2026q2/000503.html REF https://www.openwall.com/lists/oss-security/2026/04/21/1

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