CVE-2026-24881: In GnuPG before 2.5.17, a crafted CMS (S/MIME) EnvelopedData message carrying an oversized wrapped session key

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HIGH 8.1REMOTEUPGRADEUPGRADE

CVE-2026-24881 is a high-severity flaw (CVSS 8.1) affecting gnupg, gpg4win. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-121
Published	2026-01-27
Last modified	2026-07-15

Publisher (CNA): MITRE · Vendor: gnupg · gpg4win

Last updated 2026-07-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-01-27 19:16 UTCPublished CVE record published
2026-07-15 02:18 UTCUpdated Record last modified

gnupg gnupg UPGRADE

Affected: >= 2.5.13 and < 2.5.17

Fixed in: 2.5.17

Safe to downgrade to: a release before 2.5.13

1. Check installed version

apt-cache policy gnupg || rpm -q gnupg || gnupg --version

2. UPGRADE to 2.5.17 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade gnupg

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade gnupg

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 2.5.13 (Debian / Ubuntu)

apt-cache madison gnupg sudo apt install gnupg=<VERSION_BEFORE_2.5.13> sudo apt-mark hold gnupg

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list gnupg sudo dnf downgrade gnupg-<VERSION_BEFORE_2.5.13> sudo dnf versionlock add gnupg

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

gpg4win gpg4win UPGRADE

Affected: >= 5.0.0 and < 5.0.1

Fixed in: 5.0.1

Safe to downgrade to: a release before 5.0.0

1. Check installed version

apt-cache policy gpg4win || rpm -q gpg4win || gpg4win --version

2. UPGRADE to 5.0.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade gpg4win

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade gpg4win

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 5.0.0 (Debian / Ubuntu)

apt-cache madison gpg4win sudo apt install gpg4win=<VERSION_BEFORE_5.0.0> sudo apt-mark hold gpg4win

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list gpg4win sudo dnf downgrade gpg4win-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add gpg4win

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

Fedora ELN · openjpeg · FIXED · 2.5.4-5.eln159 · FEDORA-2026-1a5f60f401 · source

sudo dnf upgrade --advisory=FEDORA-2026-1a5f60f401

Fedora 46 · trustedqsl · FIXED · 2.8.7-1.fc46 · FEDORA-2026-6b1bc90ebc · source

sudo dnf upgrade --advisory=FEDORA-2026-6b1bc90ebc

Debian 12 · gnupg2 · NOT AFFECTED

Debian 13 · gnupg2 · NOT AFFECTED

RHEL 10 · gnupg2 · NOT AFFECTED

RHEL 6 · gnupg2 · DEFERRED

RHEL 7 · gnupg2 · NOT AFFECTED

RHEL 8 · gnupg2 · NOT AFFECTED

RHEL 9 · gnupg2 · NOT AFFECTED

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: dev.gnupg.org/T8044

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-24881?

gnupg: upgrade to 2.5.17; gpg4win: upgrade to 5.0.1. Exact commands for each OS are on this page.

Is CVE-2026-24881 being exploited?

CVE-2026-24881 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-24881 affect?

CVE-2026-24881 affects gnupg, gpg4win. Severity is high (CVSS 8.1). 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

How urgent is CVE-2026-24881?

Priority 58/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

GnuPG vulnerabilities

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References

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