Erlang/OTP Updates Fix TLS Authentication and Denial-of-Service Flaws
Tech GuruQuick Answer
Erlang/OTP has fixed three distinct issues in ssl, asn1 and ssh. Update to the matching patched OTP branch below. Restricting clients to TLS 1.2 is a temporary workaround for the TLS 1.3 authentication bypass only; it does not fix the other two flaws.
Confirm Scope And Apply The Supported Fix
What to do now: Inventory the OTP runtime and loaded ssl/asn1/ssh application versions used by each service, not only the system package version. Plan the branch-supported runtime update with application owners.
Source check: 2026-10-02 UTC. This notice reflects the primary-source evidence described below, not a completed update or exploitation test. Recheck the advisory and supported distribution channel before changing production.
Scope And Authority
| Product scope | Erlang/OTP ssl, asn1, and ssh applications in supported OTP 27, 28, and 29 streams |
|---|---|
| Advisory | GHSA-rgxr-4g4w-j875 / GHSA-qghx-23m5-r55m / GHSA-qhcm-px9c-rvfh |
| CVEs | CVE-2026-65634, CVE-2026-68956, CVE-2026-89422 |
| Authoritative release date | 2026-09-22 GHSA publication times: TLS 08:34:34Z; ASN.1 08:35:10Z; SSH 08:38:50Z. |
| Authority revision date | Each checked GHSA has updated_at equal to its own publication time. The SSH publication time is not a revision of the TLS advisory. |
| Affected versions | OTP 22.2 and later for the TLS flaw, OTP 17 and later for ASN.1 decoding, and OTP 18.1.2 and later for SSH, below the branch-specific patched releases. |
| Fixed version | OTP 27.3.4.18: ssl 11.2.12.13, asn1 5.3.4.3, ssh 5.2.11.13.OTP 28.5.0.7: ssl 11.6.0.6, asn1 5.4.3.1, ssh 5.5.2.6.OTP 29.1.1: ssl 11.7.7, asn1 5.5.2, ssh 6.0.6.Use a supported patched release in the appropriate branch and the project's OTP version-comparison rules. |
| CVSS base score | 7.1 / 8.2 / 9.3 (CVSS v4.0) |
| CVSS severity | High to Critical |
| Exploitation status | The three Erlang project advisories does not state that these flaws are being exploited. That is not confirmation that exploitation has not occurred. |
What Changed
CVE-2026-89422 lets a malicious peer bypass server-certificate authentication in an affected TLS 1.3 client, even with peer verification enabled. CVE-2026-65634 causes excessive CPU work when ASN.1 parses untrusted OIDs, including peer certificates. CVE-2026-68956 lets an authenticated SSH client exhaust VM memory with idle session channels; existing max_channels settings do not count those idle channels before the patch.
What To Validate Now
- Inventory. Locate Erlang/OTP ssl, asn1, and ssh applications in supported OTP 27, 28, and 29 streams deployments, versions, enabled features, exposure paths, owners, and dependent services.
- Establish applicability. Compare each deployment with the authority's affected-version statement: OTP 22.2 and later for the TLS flaw, OTP 17 and later for ASN.1 decoding, and OTP 18.1.2 and later for SSH, below the branch-specific patched releases. Do not infer applicability from product family or severity alone.
- Remediate. Deploy the matching patched OTP/component set. A temporary TLS1.2-only client restriction avoids the TLS1.3 bypass at the cost of TLS1.3 support; apply the patch to restore normal protocol support safely.
- Validate. Read back running OTP and component versions, test TLS server-certificate verification and normal client connections, and exercise representative SSH sessions and concurrency limits. Check service health after runtime restart.
- Retain evidence. Preserve asset and owner identifiers, the applicability decision, before-and-after versions, change approval, installation output, validation results, and any exception or rollback record.
Operational Cautions
Do not disable peer-certificate verification to avoid the ASN.1 parsing flaw; that removes an authentication safeguard. The ASN.1 advisory has no workaround. SSH connection/memory restrictions reduce exposure but do not fully prevent the idle-channel flaw; old idle-time and heap limits are not fixes. Patched SSH defaults limit channels to 256 and sessions to 1024, so test workloads that previously depended on unlimited concurrency. Preserve the rollback plan without treating an old exposed runtime as a resolved state.
Evidence To Retain
- Exact product, release stream, package or application version, enabled feature, environment, and accountable owner.
- UTC timestamps, authority revision, approved change record, installer or package-manager output, and resulting version.
- Relevant logs and monitoring evidence, test results, exceptions, compensating controls, and rollback decisions.
Related TechGeeks Resources
Authoritative References
Correction policy: If the authority changes affected versions, fixed versions, severity, exploitation information, mitigations, or required action, TechGeeks will update this notice and its verification date.
