CVE-2026-53422: Observable Response Discrepancy vulnerability in Erlang OTP ssh (ssh_sftpd module) allows an authenticated SFT

Routine

MEDIUM 4.3UPGRADEUPGRADE

CVE-2026-53422 is a medium-severity flaw (CVSS 4.3) affecting erlang\/otp, erlang\/ssh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Observable Response Discrepancy vulnerability in Erlang OTP ssh (ssh_sftpd module) allows an authenticated SFTP user to enumerate the existence of files and directories outside the configured root directory. The SSH_FXP_REALPATH handler in ssh_sftpd calls relate_file_name/3 with Canonicalize=false, unlike every other SFTP operation handler. This allows .. components in the requested path to bypass the is_within_root/2 check without being resolve

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	4.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-204
Published	2026-07-02
Last modified	2026-10-25

Publisher (CNA): EEF · Vendor: erlang

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-02 17:17 UTCPublished CVE record published
2026-10-25 21:10 UTCUpdated Record last modified

erlang erlang\/otp UPGRADE

Affected: >= 17.0 and < 27.3.4.14 · >= 28.0 and < 28.5.0.3 · >= 29.0 and < 29.0.3

Fixed in: 27.3.4.14, 28.5.0.3, 29.0.3

Safe to downgrade to: a release before 17.0

1. Check installed version

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

2. UPGRADE to 27.3.4.14 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade erlangotp

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 17.0 (Debian / Ubuntu)

apt-cache madison erlangotp sudo apt install erlangotp=<VERSION_BEFORE_17.0> sudo apt-mark hold erlangotp

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

dnf --showduplicates list erlangotp sudo dnf downgrade erlangotp-<VERSION_BEFORE_17.0> sudo dnf versionlock add erlangotp

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.

erlang erlang\/ssh UPGRADE

Affected: >= 3.0.1 and < 5.2.11.9 · >= 5.3 and < 5.5.2.2 · >= 6.0 and < 6.0.2

Fixed in: 5.2.11.9, 5.5.2.2, 6.0.2

Safe to downgrade to: a release before 3.0.1

1. Check installed version

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

2. UPGRADE to 5.2.11.9 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade erlangssh

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 3.0.1 (Debian / Ubuntu)

apt-cache madison erlangssh sudo apt install erlangssh=<VERSION_BEFORE_3.0.1> sudo apt-mark hold erlangssh

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

dnf --showduplicates list erlangssh sudo dnf downgrade erlangssh-<VERSION_BEFORE_3.0.1> sudo dnf versionlock add erlangssh

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.

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-2026-53422?

erlang\/otp: upgrade to 27.3.4.14, 28.5.0.3, 29.0.3; erlang\/ssh: upgrade to 5.2.11.9, 5.5.2.2, 6.0.2. Exact commands for each OS are on this page.

Is CVE-2026-53422 being exploited?

CVE-2026-53422 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-2026-53422 affect?

CVE-2026-53422 affects erlang\/otp, erlang\/ssh. Severity is medium (CVSS 4.3). Observable Response Discrepancy vulnerability in Erlang OTP ssh (ssh_sftpd module) allows an authenticated SFTP user to enumerate the existence of files and directories outside the configured root directory. The SSH_FXP_REALPATH handler in

How urgent is CVE-2026-53422?

Priority 20/100. No elevated risk signals yet.

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References

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