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VulnerabilityPublished Updated

CVE-2026-68956: Erlang OTP · Unthrottled Resource Allocation

Affects Erlang OTPSource CVE Database V5

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Not known to be exploited · CVSS 7.1 High : upgrade to 27.3.4.18 soon.

Data as of 5 Nov 2026, 23:24 UTC

CVSS 4.0 base score
7.1High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.3% chance of exploitation in 30 days – higher than 31% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 27.3.4.18, 5.2.11.13
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 22 Sep 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 6 Nov 2026.

What to do

Upgrade OTP to 27.3.4.18; OTP and ssh to 5.2.11.13.

Affected software

ProductAffectedFixed in
ErlangOTPAffected
  • >=18.1.2 <27.3.4.18
Fixed in
  • 27.3.4.18
ErlangOTPAffected
  • >=4.1.1 <5.2.11.13
Fixed in
  • 5.2.11.13
ErlangOTPAffected
  • ≥ 84df3d4d0278e21a36a453bfee94799f0df67c2a, < 79c2d2be17d902c5f53969b5806b725efda831be
Fixed in–
GitHubsshpkg:github/sshOther threatsAffected
  • >=4.1.1 <5.2.11.13
Fixed in
  • 5.2.11.13

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, limiting authenticated access and monitoring for unusual ssh session channel activity may help reduce risk.

Description

Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler. The "session" clause of ssh_connection:handle_msg/4 checks only minimal_remote_max_packet_size before calling setup_session/5, which unconditionally builds a #channel{} record and stores it in the ETS channel cache. The max_channels daemon option is consulted only by ssh_channel_sup:max_num_channels_not_exceeded/2, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable. This issue affects OTP from OTP 18.1.2 before OTP 27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP 18.1.2, corresponding to ssh before 4.1.1, is affected is unknown.

References

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