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GnuPG CVE-2026-24881

CRITICAL
Stack-based Buffer Overflow (CWE-121)
2026-01-27 cve@mitre.org
RCE Buffer Overflow Stack Overflow Denial Of Service Gnupg Gpg4win
9.8
CVSS 3.1 · NVD
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Severity by source

NVD PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
8.8 HIGH

Network-delivered crafted message needs no authentication, but a victim must attempt decryption (UI:R); overflow in the key-handling agent yields full C/I/A impact.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Red Hat
8.1 HIGH
qualitative

Primary rating from NVD.

CVSS VectorNVD

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

Lifecycle Timeline

11
Analysis Updated
Jun 30, 2026 - 04:04 vuln.today
v5 (cvss_changed)
Analysis Updated
Jun 30, 2026 - 04:03 vuln.today
v4 (cvss_changed)
Analysis Updated
Jun 30, 2026 - 04:02 vuln.today
v3 (cvss_changed)
Analysis Updated
Jun 30, 2026 - 04:01 vuln.today
v2 (cvss_changed)
Re-analysis Queued
Jun 30, 2026 - 03:23 vuln.today
cvss_changed
Severity Changed
Jun 30, 2026 - 03:23 NVD
HIGH CRITICAL
CVSS changed
Jun 30, 2026 - 03:23 NVD
8.1 (HIGH) 9.8 (CRITICAL)
Patch released
Apr 09, 2026 - 20:30 nvd
Patch available
Analysis Generated
Mar 12, 2026 - 21:55 vuln.today
PoC Detected
Feb 12, 2026 - 18:15 vuln.today
Public exploit code
CVE Published
Jan 27, 2026 - 19:16 nvd
HIGH 8.1

DescriptionNVD

In GnuPG before 2.5.17, a crafted CMS (S/MIME) EnvelopedData message carrying an oversized wrapped session key can cause a stack-based buffer overflow in gpg-agent during PKDECRYPT--kem=CMS handling. This can easily be leveraged for denial of service; however, there is also memory corruption that could lead to remote code execution.

AnalysisAI

Remote code execution and denial of service in GnuPG before 2.5.17 stem from a stack-based buffer overflow in gpg-agent when it processes a crafted CMS (S/MIME) EnvelopedData message containing an oversized wrapped session key during PKDECRYPT --kem=CMS handling. Any user or service decrypting attacker-supplied S/MIME mail with a vulnerable build can be crashed, and the memory corruption may be escalated to arbitrary code execution in the gpg-agent process that custodies private keys. Publicly available exploit code exists, but the issue is not in CISA KEV and EPSS is low (0.20%, 41st percentile), indicating no confirmed widespread exploitation yet.

Technical ContextAI

GnuPG is the reference OpenPGP/CMS implementation used for mail encryption, package signing, and key management across Linux distributions and the Windows Gpg4win distribution. The flaw lives in gpg-agent, the daemon that holds private keys and performs cryptographic operations on their behalf; specifically in the newer KEM (Key Encapsulation Mechanism) decryption path exposed via the PKDECRYPT --kem=CMS Assuan command. When parsing a CMS EnvelopedData structure (the S/MIME container that wraps a per-message symmetric session key encrypted to the recipient's certificate), an attacker-controlled length field for the wrapped session key is not properly bounded before the key material is copied into a fixed-size stack buffer. This is a classic CWE-121 stack-based buffer overflow, where the overflow can smash the return address and adjacent stack data, enabling control-flow hijack beyond a simple crash.

RemediationAI

Vendor-released patch: GnuPG 2.5.17 - upgrade all GnuPG and Gpg4win installations to 2.5.17 or later, and on Linux apply the corresponding distribution security update once published (track Red Hat's advisory and VEX at https://access.redhat.com/security/cve/CVE-2026-24881 and https://bugzilla.redhat.com/show_bug.cgi?id=2433480). Until patched, the most effective compensating control is to avoid invoking the affected path: do not process untrusted S/MIME (CMS EnvelopedData) messages with the vulnerable gpg-agent, and disable or quarantine automated S/MIME decryption in mail gateways and pipelines that pass attacker-reachable content to gpg-agent - the trade-off is loss of automatic S/MIME inbound decryption until upgraded. Where feasible, restrict and isolate gpg-agent (run under a constrained service account, limit who can submit PKDECRYPT requests over the Assuan socket) to contain a crash or code-execution attempt; the side effect is added operational friction for legitimate key operations. Verify the running version with gpg-agent --version after upgrading rather than relying on package metadata alone.

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Same weakness CWE-121 – Stack-based Buffer Overflow

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Vendor StatusVendor

SUSE

Severity: High
Product Status
openSUSE Tumbleweed Fixed
SLES15-SP5-CHOST-BYOS-SAP-CCloud Fixed
SLES15-SP6-CHOST-BYOS Fixed
SLES15-SP6-CHOST-BYOS-Aliyun Fixed
SLES15-SP6-CHOST-BYOS-Azure Fixed

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CVE-2026-24881 vulnerability details – vuln.today
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