CVE-2026-48859: Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthent

Routine

MEDIUM 5.3REMOTEUPGRADEUPGRADE

CVE-2026-48859 is a medium-severity flaw (CVSS 5.3) affecting erlang\/otp, erlang\/ssh. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication. When the SSH daemon is configured with the user_passwords or password option, ssh_auth:check_password/3 performs a PBKDF2-SHA256 computation with 600,000 iterations (~300ms) for valid usernames, but returns immediately (~0ms) for invalid usernames via

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 71%)
CISA exploited list	No
Weakness	CWE-208
Published	2026-06-10
Last modified	2026-10-26

Publisher (CNA): EEF · Vendor: erlang

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-10 16:17 UTCPublished CVE record published
2026-10-26 11:10 UTCUpdated Record last modified

erlang erlang\/otp UPGRADE

Affected: >= 29.0 and < 29.0.2

Fixed in: 29.0.2

Safe to downgrade to: a release before 29.0

1. Check installed version

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

2. UPGRADE to 29.0.2 (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 29.0 (Debian / Ubuntu)

apt-cache madison erlangotp sudo apt install erlangotp=<VERSION_BEFORE_29.0> 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_29.0> 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: >= 6.0 and < 6.0.1

Fixed in: 6.0.1

Safe to downgrade to: a release before 6.0

1. Check installed version

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

2. UPGRADE to 6.0.1 (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 6.0 (Debian / Ubuntu)

apt-cache madison erlangssh sudo apt install erlangssh=<VERSION_BEFORE_6.0> 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_6.0> 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-2026-48859?

erlang\/otp: upgrade to 29.0.2; erlang\/ssh: upgrade to 6.0.1. Exact commands for each OS are on this page.

Is CVE-2026-48859 being exploited?

CVE-2026-48859 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-2026-48859 affect?

CVE-2026-48859 affects erlang\/otp, erlang\/ssh. Severity is medium (CVSS 5.3). Observable Timing Discrepancy vulnerability in Erlang/OTP ssh (ssh_auth, ssh_options modules) allows unauthenticated remote username enumeration via timing side-channel in password authentication. When the SSH daemon is configured with the

How urgent is CVE-2026-48859?

Priority 31/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-49759 HIGH 8.2 UPGRADE UPGRADE Stack-based Buffer Overflow vulnerability in Erlang OTP erts (inet_drv) allows an unauthenticated remote attac
CVE-2026-42790 HIGH 8.1 UPGRADE Improper Certificate Validation vulnerability in Erlang OTP public_key (pubkey_cert and public_key modules) al
CVE-2026-42789 MEDIUM 4.8 UPGRADE Improper Following of a Certificate's Chain of Trust vulnerability in Erlang OTP public_key (pubkey_cert modul
CVE-2026-48856 MEDIUM 6.5 UPGRADE UPGRADE Sensitive Data Exposure vulnerability in Erlang OTP inets (httpc_response module) allows Retrieve Embedded Sen
CVE-2026-48860 MEDIUM 6.5 UPGRADE UPGRADE Reliance on IP Address for Authentication vulnerability in Erlang/OTP ssl (inet_tls_dist module) allows unauth

References

← Back to latest CVEs