CVE-2026-68956
CVE-2026-68956 — SSH daemon allocates unbounded idle session channels, bypassing max_channels
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 17.0 before OTP 27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to ssh from 3.0.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP 17.0, corresponding to ssh before 3.0.1, is affected is unknown.
Published Updated Sources: NVD, Erlang (CNA), GitHub, SOCRadar CTI
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Exploit code
public exploit, none observed
EPSS
0%
ahead of 0% of scored CVEs
CVSS base
7.1
high
Remediation
The vendor's own words where we have them.
Upgrade OTP to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.
First 24 hours
Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.
- Identify exposed assets running affected vendor/product/version combinations.
- Prioritize based on EPSS, PoC availability, and external exposure.
- Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.
Affected scope
Vendor, product and version as the advisories word them.
| Vendor | Product | Versions | Status |
|---|---|---|---|
| Erlang | OTP | 17.0 | Vulnerable |
| Erlang | OTP | 3.0.1 | Vulnerable |
| Erlang | OTP | 84adefa331c4159d432d22840663c38f155cd4c1 | Vulnerable |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Attack Complexity
Low
Attack Vector
Network
Privileges Req
Low
User Interaction
None
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 7.1 | CVSS 4.0 | high | — | — | Erlang (CNA) |
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
What this weakness leads to
MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.
CWE-770 · Allocation of Resources Without Limits or Throttling
- DoS: Resource Consumption (CPU)
- DoS: Resource Consumption (Memory)
- DoS: Resource Consumption (Other)
Mitigation: Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
Weakness & attack patterns
- CWE-770
Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.
- T1498.001Network Denial of Service: Direct Network Flood
- T1499Endpoint Denial of Service
- T1499.003Endpoint Denial of Service: Application Exhaustion Flood
Public exploit
Capability, not use: code existing is a different claim from anyone running it.
Repositories
1
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /OTP, /4, /5, /2.
- Prioritize edge telemetry for network-reachable OTP.
- Monitor for scanner or exploit-pattern traffic after 1 public PoC repositories were reported.
Timeline
What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.
- 2026
Added · CVSS 3.1 7.1 (AV:N)
Sep 22, 2026 · NVD
Initial · CVE published
Sep 22, 2026 · NVD
CVE published by MITRE.
Sep 22, 2026 · SOCRadar CTI
References
8 on the record
- cna.erlef.org/cves/CVE-2026-68956.html
Vendor Advisory, Mitre
- github.com/erlang/otp/commit/79c2d2be17d902c5f53969b5806b725efda831be
Exploit, Third Party Advisory, Mitre
- github.com/erlang/otp/commit/e18100975f0e5a8d59d02de00df12247a91b443b
Exploit, Third Party Advisory, Mitre
- github.com/erlang/otp/commit/e2bbad0107bba41491a4d549686fd023db8740da
Exploit, Third Party Advisory, Mitre
- github.com/erlang/otp/security/advisories/GHSA-qhcm-px9c-rvfh
Exploit, Third Party Advisory, Mitre
- osv.dev/vulnerability/EEF-CVE-2026-68956
Vendor Advisory
- www.erlang.org/doc/system/versions.html#order-of-versions
Vendor Advisory
- www.erlang.org/doc/system/versions.html%23order-of-versions
Mitre
Elsewhere on this site
- Erlangevery CVE for this vendor
- Denial of Servicesame class
- CWE-770other pages naming this weakness
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record1
What should defenders know first?
CVE-2026-68956 is SSH daemon allocates unbounded idle session channels, bypassing max_channels, a high vulnerability affecting OTP from Erlang. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-68956. Public exploit evidence is: 1 public PoC repositories reported; 0 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 7.1 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.