CVE-2026-55953: TLS 1.2 and DTLS client accepts unoffered anonymous cipher suite, bypassing server authentication
CVE-2026-55953 is a vulnerability in TLS 1.2 and DTLS client accepts unoffered anonymous cipher suite, bypassing server authentication, rated Important by Microsoft, with a CVSS 3.1 base score of 7.7 (High). An attacker can exploit it remotely over the network, without any privileges and without user interaction. Microsoft has not reported exploitation in the wild. The EPSS model estimates a 0.23% probability of exploitation activity in the next 30 days, higher than 14% of all scored vulnerabilities. Microsoft released the fix on 6 August 2026, outside Patch Tuesday. It affects 1 product in 1 product family (Open Source Software).
Key facts
- CVE ID
- CVE-2026-55953
- Severity
- High CVSS 7.7
- Microsoft severity
- Important
- Exploited in the wild
- No
- Publicly disclosed
- No
- Weakness
- CWE-757
- EPSS
- 0.23% (percentile 14%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- July 2026 Patch Tuesday
- Product families
- Open Source Software
CVSS score and vector
Microsoft scores CVE-2026-55953 at 7.7 (temporal 7.1) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:L/E:U
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | High |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | Low |
| Exploit code maturity | Unproven |
NVD scores it 7.4 (HIGH) with CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N.
Affected products (1)
Open Source Software
| Product | Security update | Type | Fixed build | Restart |
|---|---|---|---|---|
| azl3 erlang 26.2.5.21-4 on Azure Linux 3.0 | CBL-Mariner Releases | Security Update | 26.2.5.21-3 | No |
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 7.4 (HIGH)
- NVD weakness
- CWE-757
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| erlang\/otp | from 17.0, before 27.3.4.15 |
| erlang\/otp | from 28.0, before 28.5.0.4 |
| erlang\/otp | from 29.0, before 29.0.4 |
| erlang\/ssl | from 5.3.4, before 11.2.12.11 |
| erlang\/ssl | from 11.3, before 11.6.0.4 |
| erlang\/ssl | from 11.7, before 11.7.4 |
References
- https://cna.erlef.org/cves/CVE-2026-55953.html (Patch, Third Party Advisory)
- https://github.com/erlang/otp/commit/064e236414614f9085cbbbd6eacf0e43c02d1b4b (Patch)
- https://github.com/erlang/otp/commit/0a82596d425abe43dc2e0b3d74aa1557ef74051c (Patch)
- https://github.com/erlang/otp/commit/e6ff938116b2872bccc478af7fefb56627285b77 (Patch)
- https://github.com/erlang/otp/security/advisories/GHSA-c6cw-pr89-w882 (Vendor Advisory)
- https://osv.dev/vulnerability/EEF-CVE-2026-55953 (Patch, Third Party Advisory)
- https://www.erlang.org/doc/system/versions.html#order-of-versions (Release Notes)
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |