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VulnerabilityPublished

CVE-2026-123612: rustls · Incorrect Behavior Order

Affects rustlsSource CVE Database V5

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Not known to be exploited · CVSS 4.6 Medium : upgrade to 0.23.46 when convenient.

Data as of 8 Nov 2026, 01:50 UTC

CVSS 4.0 base score
4.6Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (VulnCheck)CVSS 4.04.6
CNA (VulnCheck)CVSS 3.12.3
Patch
Available – fixed in 0.23.46
CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 8 Nov 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.

What to do

Upgrade rustls to 0.23.46.

Affected software

ProductAffectedFixed in
rustlsrustlsAffected
  • >=0.23.44 <0.23.46
Fixed in
  • 0.23.46
crates.iorustlspkg:cargo/rustlsOther threatsAffected
  • >=0.23.44 <0.23.46
Fixed in
  • 0.23.46

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade rustls to version 0.23.46 or later, where this issue is fixed. No other mitigation is indicated or required.

Description

An information disclosure vulnerability exists in rustls versions 0.23.44 and 0.23.45. When Encrypted Client Hello (ECH) is rejected, application data buffered before handshake completion is sent to the client-facing server instead of being properly isolated. This occurs because start_traffic() queues plaintext data before sending the ech_required alert, causing the authenticated public_name server to receive data intended for the inner server. The issue is fixed in rustls version 0.23.46.

References

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