CVE-2023-38408: The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leadin

Q: How do I fix CVE-2023-38408?

openssh: upgrade to 9.3; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2023-38408 being exploited?

CVE-2023-38408 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2023-38408 affect?

CVE-2023-38408 affects openssh, fedora. Severity is critical (CVSS 9.8). The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remote code execution if an agent is forwarded to an attacker-controlled system. (Code in /usr/lib is not necessarily safe fo

Q: How urgent is CVE-2023-38408?

Priority 77/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

This week

CRITICAL 9.8REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2023-38408 is a critical-severity flaw (CVSS 9.8) affecting openssh, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remote code execution if an agent is forwarded to an attacker-controlled system. (Code in /usr/lib is not necessarily safe for loading into ssh-agent.) NOTE: this issue exists because of an incomplete fix for CVE-2016-10009.

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	79.7% (top 1%)
CISA exploited list	No
Weakness	CWE-428
Published	2023-07-20
Last modified	2026-10-15

Publisher (CNA): MITRE · Vendor: fedoraproject · openbsd

Last updated 2026-10-15 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-07-20 03:15 UTCPublished CVE record published
2026-10-15 00:16 UTCUpdated Record last modified

openbsd openssh UPGRADE

Affected: < 9.3 · 9.3 · 9.3 p1

Fixed in: 9.3

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 9.3 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openssh

Note

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

fedoraproject fedora MITIGATE

Affected: 37 · 38

Fixed in: no fixed release known

Safe to downgrade to: a release before 37

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · borgmatic · FIXED · 2.2.0-1.fc46 · FEDORA-2026-041229e71b · source

sudo dnf upgrade --advisory=FEDORA-2026-041229e71b

Fedora ELN · pie · FIXED · 1.5.4-1.eln159 · FEDORA-2026-a2c0261d3a · source

sudo dnf upgrade --advisory=FEDORA-2026-a2c0261d3a

Ubuntu 20.04 · openssh · FIXED · 1:8.2p1-4ubuntu0.8

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:8.2p1-4ubuntu0.8" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 22.04 · openssh · FIXED · 1:8.9p1-3ubuntu0.3

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:8.9p1-3ubuntu0.3" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.04 · openssh · FIXED · 1:9.3p1-1ubuntu2

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:9.3p1-1ubuntu2" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 24.10 · openssh · FIXED · 1:9.3p1-1ubuntu2

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:9.3p1-1ubuntu2" && echo PATCHED || echo STILL-VULNERABLE

Ubuntu 25.04 · openssh · FIXED · 1:9.3p1-1ubuntu2

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:9.3p1-1ubuntu2" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · openssh · FIXED · 1:9.2p1-2+deb12u1

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:9.2p1-2+deb12u1" && echo PATCHED || echo STILL-VULNERABLE

Debian 13 · openssh · FIXED · 1:9.3p2-1

sudo apt update && sudo apt install --only-upgrade openssh dpkg --compare-versions "$(dpkg-query -W -f='${Version}' openssh)" ge "1:9.3p2-1" && echo PATCHED || echo STILL-VULNERABLE

RHEL 6 Extended Lifecycle Support · openssh · FIXED · openssh-5.3p1-125.el6_10

sudo dnf upgrade --advisory=RHSA-2023:4428 rpm -q openssh

RHEL 7 · openssh · FIXED · openssh-7.4p1-23.el7_9

sudo dnf upgrade --advisory=RHSA-2023:4382 rpm -q openssh

RHEL 8 · openssh · FIXED · openssh-8.0p1-19.el8_8

sudo dnf upgrade --advisory=RHSA-2023:4419 rpm -q openssh

RHEL 8.1 Update Services for SAP Solutions · openssh · FIXED · openssh-8.0p1-5.el8_1.1

sudo dnf upgrade --advisory=RHSA-2023:4383 rpm -q openssh

RHEL 8.2 Advanced Update Support · openssh · FIXED · openssh-8.0p1-5.el8_2

sudo dnf upgrade --advisory=RHSA-2023:4384 rpm -q openssh

Alpine 3.20 · openssh · NOT AFFECTED

Alpine 3.21 · openssh · NOT AFFECTED

Alpine 3.22 · openssh · NOT AFFECTED

Alpine 3.23 · openssh · NOT AFFECTED

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2023-273 · source

sudo dnf update --advisory=ALAS2023-2023-273

Amazon Linux 2 · see advisory · FIXED · ALAS2-2023-2176 · source

sudo yum update --advisory=ALAS2-2023-2176

Amazon Linux 1 · see advisory · FIXED · ALAS-2023-1802 · source

sudo yum update --advisory=ALAS-2023-1802

Public exploits and detection

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

GitHub PoC: kali-mx/CVE-2023-38408 (53 stars)
GitHub PoC: LucasPDiniz/CVE-2023-38408 (45 stars)
GitHub PoC: TX-One/CVE-2023-38408 (7 stars)
Write-up: blog.qualys.com/vulnerabilities-threat-research/2023/07/19/cve-2023-38408-remote-code-exec
Write-up: news.ycombinator.com/item?id=36790196
Write-up: www.vicarius.io/vsociety/posts/exploring-opensshs-agent-forwarding-rce-cve-2023-38408
GitHub PoC: Adel2411/cve-2023-38408

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-2023-38408?

openssh: upgrade to 9.3; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-38408 being exploited?

CVE-2023-38408 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-2023-38408 affect?

CVE-2023-38408 affects openssh, fedora. Severity is critical (CVSS 9.8). The PKCS#11 feature in ssh-agent in OpenSSH before 9.3p2 has an insufficiently trustworthy search path, leading to remote code execution if an agent is forwarded to an attacker-controlled system. (Code in /usr/lib is not necessarily safe fo

How urgent is CVE-2023-38408?

Priority 77/100. Critical severity; EPSS top 1%: very likely to be exploited; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action; On your watchlist

Software pages

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References

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