CVSS 4.0
4.6 mediumCVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:NCVE-2026-123612
Medium (4.6) in rustls rustls. EPSS 0.1% estimated probability of exploitation activity in the next 30 days. Fixed in rustls 0.23.46, 0.24.0-dev.2.
On this page
rustls 0.23.44 and 0.23.45 contain an information disclosure vulnerability that sends application data buffered before the handshake completes to the client-facing server when Encrypted Client Hello is rejected. Because start_traffic() queues plaintext from ClientConnection::writer() before sending the ech_required alert, the authenticated public_name server receives data intended for the inner server.
Severity
CVSS 3.1
2.3 lowCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N- EPSS
- 0.1% estimated probability of exploitation activity in the next 30 days; 1st percentile. Scored 2026-11-10. A forecast for this CVE across the internet, not for your own systems.
- CWE
- CWE-696 Incorrect Behavior Order
- Published
- NVD analysis
- Awaiting analysis
- Record from
- the NVD, synced
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Explain CVE-2026-123612 for an engineer deciding whether to act. Use https://cve.bz/api/public/cves/CVE-2026-123612?via=ask-ai-copy and https://cve.bz/cve/CVE-2026-123612?via=ask-ai-copy as the source of truth: what is affected and which versions fix it, whether it is in CISA KEV, public exploits, and its EPSS (an internet-wide 30-day estimate of exploitation activity, not a forecast for my systems). If they give no fixed versions, use the CVE record https://cveawg.mitre.org/api/cve/CVE-2026-123612 or the vendor advisory, not third-party mirrors. Tell me how to check whether I am affected and how to verify a fix. Cite the sources and say where they are uncertain.Opens a third-party assistant; its answer is its own, not cve.bz's. The prompt holds only this CVE's id and public links.
Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| rustls | from 0.23.44 before 0.23.46 |
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-vp88-798v-h67f | crates.io | rustls | >=0.23.44 <0.23.46 | 0.23.46 |
| GHSA-vp88-798v-h67f | crates.io | rustls | >=0.24.0-dev.1 <0.24.0-dev.2 | 0.24.0-dev.2 |
| RUSTSEC-2026-0347 | crates.io | rustls | >=0.23.44 <0.23.46 | 0.23.46 |
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Debian | 12, 13, 14 | rust-rustls | no fix listed | DEBIAN-CVE-2026-123612 |
| Ubuntu | 24.04:LTS, 26.04:LTS, 26.10 | rust-rustls | no fix listed | UBUNTU-CVE-2026-123612 |
From the distributions' data via OSV.dev: the Debian Security Tracker; Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian · Ubuntu.
Attack patterns (CAPEC)
- CAPEC-463 Padding Oracle Crypto Attack Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.