rustls 0.23.44 and 0.23.45 ECH Rejection Application Data Disclosure
- Exploited
- No known exploitation
- Fix
- Fixed in 0.23.46
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 0.23.46.
- Published
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 15/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
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.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure?/25Unknown. No advisory context yet
- Reach10/20Affects crates.io packages
- Severity4.6/10CVSS 4.6
- No patch0/5No signal
What would change the score
- Would score about 70 if added to CISA KEV
- Would score about 65 if CISA's SSVC rates exploitation active
- Would score about 37 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 0.23.46.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- rustls rustls
From 0.23.44 · fixed in 0.23.46
- rustlscrates.io
From 0.23.44 · fixed in 0.23.46
Evidence 2
- Advisory
- Link
Corrections
None so far.
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Questions about CVE-2026-123612
Is CVE-2026-123612 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-123612?
rustls: from 0.23.44 before 0.23.46. rustls (crates.io): from 0.23.44 before 0.23.46.Source: cve.now feed data
How do I fix CVE-2026-123612?
Upgrade to a fixed version: 0.23.46.Source: cve.now feed data