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VulnerabilityPublished

Rustls: Session Debug formatting exposes TLS master secrets and resumption PSKs

Affects rustlsSource GCVE Database

0

CVSS 4.0 Medium : upgrade to 0.23.46 when convenient.

Data as of 27 Oct 2026, 17:42 UTC

CVSS 3.1 base score
4.0Medium
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 0.23.46, 0.24.0-dev.2
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N

What to do

Upgrade rustls to 0.23.46; rustls to 0.24.0-dev.2.

Affected software

ProductAffectedFixed in
crates.iorustlsAffected
  • <0.23.46
Fixed in
  • 0.23.46
crates.iorustlsAffected
  • >=0.24.0-dev.1 <0.24.0-dev.2
Fixed in
  • 0.24.0-dev.2

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AI-suggested

A patch is available and should be applied by upgrading rustls to version 0.23.46 or later, or to 0.24.0-dev.2 or later. Users should avoid logging or formatting client session values with Debug in custom ClientSessionStore implementations until patched. The vendor advisory explicitly warns that session-store values are sensitive and should be handled carefully.

Description

A vulnerability in rustls versions prior to 0.23.46 and between 0.24.0-dev.1 and 0.24.0-dev.2 allows the TLS master secret or TLS 1.3 resumption PSK to be exposed when formatting a client session value with the Debug trait. This can lead to leakage of sensitive key material if a custom ClientSessionStore logs these debug outputs. Built-in diagnostics do not expose these secrets, and the session-store interface warns about the sensitivity of these values.

References

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