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VulnerabilityPublished Updated

CVE-2026-53422: Erlang OTP · Observable Response Discrepancy

Affects Erlang OTPSource CVE Database V5

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Not known to be exploited · CVSS 2.3 Low : upgrade to 27.3.4.14 when convenient.

Data as of 14 Nov 2026, 20:58 UTC

CVSS 4.0 base score
2.3Low
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (EEF)CVSS 4.02.3
EPSS
0.2% chance of exploitation in 30 days – higher than 18% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 27.3.4.14, 5.2.11.9
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 2 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 14 Nov 2026.

What to do

Upgrade OTP to 27.3.4.14; OTP and ssh to 5.2.11.9.

Affected software

ProductAffectedFixed in
OTPotpAffected
  • >=17.0 <27.3.4.14
Fixed in
  • 27.3.4.14
OTPsshAffected
  • >=3.0.1 <5.2.11.9
Fixed in
  • 5.2.11.9
OTPerlang/otpAffected
  • ≥ 84adefa331c4159d432d22840663c38f155cd4c1, < 86622cfaacf57a02c7645d1999f946846b504c94
Fixed in–
GitHubsshpkg:github/sshOther threatsAffected
  • >=3.0.1 <5.2.11.9
Fixed in
  • 5.2.11.9

CPE configurations (1)

  • cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, limit SFTP user privileges and monitor for suspicious SFTP activity. Since the vulnerability requires authentication, controlling access to SFTP accounts reduces risk.

Description

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 resolved. The un-canonicalized path then enters resolve_symlinks/2, which walks up the directory tree above the configured root and issues read_link() syscalls on arbitrary filesystem paths. An authenticated SFTP client can exploit this by sending a REALPATH request with a crafted traversal path. The server response differs depending on whether the target path exists on the host filesystem (SSH_FXP_NAME when the path resolves successfully, SSH_FX_NO_SUCH_FILE when it does not). This creates a path-existence oracle that an attacker can use to enumerate the filesystem structure outside the configured root, including the existence of sensitive files, directories, and mount points. The vulnerability leaks only the existence of paths. No file contents, credentials, or write access are obtainable through this issue alone. The information gained may assist further attacks when combined with other vulnerabilities. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routine ssh_sftpd:handle_op/4. This issue affects OTP from OTP 17.0 before OTP 27.3.4.14, OTP 28.5.0.3, and OTP 29.0.3, corresponding to ssh from 3.0.1 before 5.2.11.9, 5.5.2.2, and 6.0.2. Whether OTP before OTP 17.0, corresponding to ssh before 3.0.1, is affected is unknown.

References

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