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TI-2026-86754 Aliases CVE-2026-123612GHSA-jrx3-hh25-gg3m

Application data sent to public_name server when rustls rejects ECH

Priority LOW 36CWE-696Published · Updated

Key facts

Attack vector
Local
Privileges required
High
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
Low · None · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

rustls from 0.23.44 before 0.23.46 is affected. When Encrypted Client Hello is rejected, rustls sends application data buffered before the handshake completes to the client-facing public_name server instead of the inner server (CWE-696). An attacker with high privileges on the local system can exploit this, and the impact is limited to confidentiality.

Written with Claude Haiku 5.5 from the sources below · 2026-11-08

Description from the CNA

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.

Why it matters now

Fix Fixed rustls (rustls): 0.23.46

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
rustlsrustls0.23.44 to before 0.23.460.23.46Patch availableCNA
  • rustls Vendorrustls Affected 0.23.44 to before 0.23.46 Fixed in 0.23.46 Patch available CNA

Remediation

Upgrade rustls to version 0.23.46.

Written with Claude Haiku 5.5 from the sources below · 2026-11-08

  • Fix · CNA rustls (rustls) Fixed in 0.23.46

Fixed in the same release

Records fixed by the same vendor advisory or release, as the CNA lists them.

  • Release ·

    rustls 0.23.46

    3 records Highest priority Priority MEDIUM 2 MEDIUM, 1 LOW

    Other records, highest priority first

    • TI-2026-86753 Key exchange downgrade in rustls via unauthenticated ServerHelloPriority MEDIUM 43
    • TI-2026-86752 Uncontrolled memory allocation in rustls Brotli certificate decompressionPriority MEDIUM 43
    Show all 3 records →

Timeline

  1. 2026-11-08 Threatist record created from CVE-2026-123612
  2. 2026-11-08 Alias added: GHSA-jrx3-hh25-gg3m

References

Advisory 1

  • TI-2026-63063 rustls-webpki before 0.103.13 Panic via empty BIT STRING CVSS 4.0HIGH 8.7
  • TI-2026-86755 Rustls accepts handshake messages at the wrong encryption level CVSS 4.0MEDIUM 6.9
  • TI-2026-86753 Key exchange downgrade in rustls via unauthenticated ServerHello CVSS 4.0MEDIUM 6.3
  • TI-2026-86752 Uncontrolled memory allocation in rustls Brotli certificate decompression CVSS 4.0MEDIUM 6.3
  • TI-2024-21532 Rustls vulnerable to an infinite loop in rustls::conn::ConnectionCommon::complete_io() with proper client input CVSS 3.1HIGH 7.5
  • TI-2026-86751 Secret key material exposed through Debug formatting in Rustls CVSS 4.0MEDIUM 4.1
See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences