CriticalPublic exploit

GnuPG gpg-agent PKDECRYPT --kem=CMS Stack Buffer Overflow

IdentifiersCVE-2026-24881CWE-121· Stack-based Buffer Overflow

CVE-2026-24881 affects GnuPG before 2.5.17. A crafted CMS (S/MIME) EnvelopedData message containing an oversized wrapped session key can trigger a stack-based buffer overflow in gpg-agent while handling PKDECRYPT with --kem=CMS. The flaw results from unsafe handling of attacker-controlled wrapped session key data during the CMS/KEM decryption path, causing stack memory corruption. The issue is readily exploitable for process crash/denial of service, and the associated memory corruption could potentially be developed into remote code execution.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can crash gpg-agent, causing denial of service for cryptographic operations that depend on the agent. Because the overflow corrupts stack memory, the impact may extend beyond availability to full compromise of the affected process, with potential remote code execution if an attacker can reliably control the corrupted state. The provided CVSS context indicates network attackability with high confidentiality, integrity, and availability impact.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by preventing untrusted CMS/S/MIME EnvelopedData from reaching vulnerable GnuPG decryption workflows, especially paths that invoke gpg-agent PKDECRYPT with --kem=CMS. Restrict or disable S/MIME/CMS decryption where feasible, isolate systems or services that process externally supplied S/MIME content, and limit remote or automated processing of untrusted encrypted messages until patched.

Remediation

Patch, then assume compromise.

Upgrade GnuPG to version 2.5.17 or later, which fixes this issue. Track the upstream GnuPG security release and associated issue/advisory references for any backports or distribution-specific patched packages.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

GnupgGnupgapplication

GnupgGpg-Agentapplication

Gpg4winGpg4winapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

13 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

13 SOURCESView more in app

the hacker newsNews

Mar 7, 2026

OpenAI Codex Security Scanned 1.2 Million Commits and Found 10,561 High-Severity Issues

Unknown

the hacker newsNews

Mar 7, 2026

OpenAI Codex Security Scanned 1.2 Million Commits and Found 10,561 High-Severity Issues

Unknown

cyber security newsNews

Mar 7, 2026

OpenAI Launches Codex Security that Discover, Validate and Patch Vulnerabilities

A stack buffer overflow in gpg-agent related to ECC KEM, reachable via PKDECRYPT.

bugflationNews

Mar 6, 2026

OpenAI Codex Security publishes OSS CVE examples - Bugflation

One of the example CVE IDs cited in OpenAI's Codex Security research-preview disclosure cluster; the content does not provide technical details of the flaw itself.

+1 more in the timeline

What this page doesn’t show

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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity8