CVE-2026-123609
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 Secret Exposure via Debug
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- High
- User interaction
- Passive
What an attacker can affect
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 Secret Exposure via Debug
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
CVE-2026-123609- CVSS 4.0
- 4.1 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-212
- Updated
- 2026-11-08
EUVDEUVD-2026-119368
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
EUVD-2026-119368- CVSS 4.0
- 4.1 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - Updated
- 2026-11-08
GitHub AdvisoriesGHSA-67mj-442h-2gp6
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure...
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
GHSA-67mj-442h-2gp6- CVSS 4.0
- 4.1 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-212
- Updated
- 2026-11-08
GitHub AdvisoriesGHSA-c8m5-c952-6cm4
Rustls: Session Debug formatting exposes TLS master secrets and resumption PSKs
Summary
Formatting a client session value with Debug exposes its TLS 1.2 master secret or TLS 1.3 resumption PSK. A custom session store that logs these values can disclose keys to readers of the logs. Ordinary connection and built-in cache diagnostics remain redacted, and the session-store interface already warns that its values are sensitive.
Details
Derived formatters traverse the session's secret-bearing fields. This conflicts with the project's explicit key-material redaction policy.
Proof of concept
Custom ClientSessionStore implementations could leak secret data by using the provided Tls12ClientSessionValue or Tls13ClientSessionValue in a way that triggers its implementation of the Debug trait.
Impact
Such store implementations could leak the master secret for the TLS connection.
Acknowledgement
Thanks to OpenAI OutboundDisclosures@openai.com for the disclosure.
- Record
GHSA-c8m5-c952-6cm4- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-212
- Updated
- 2026-11-02
NVD
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
CVE-2026-123609- CVSS 4.0
- 4.1 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-212
- Updated
- 2026-11-10
OSV
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 Secret Exposure via Debug
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
CVE-2026-123609- CVSS 4.0
- 4.1 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - Weakness
- CWE-212
- Updated
- 2026-11-08
Show 9 moreShow less
OSVDEBIAN-CVE-2026-123609
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
DEBIAN-CVE-2026-123609- CVSS 4.0
- 4.1 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Updated
- 2026-11-11
OSVGHSA-c8m5-c952-6cm4
Rustls: Session Debug formatting exposes TLS master secrets and resumption PSKs
Summary
Formatting a client session value with Debug exposes its TLS 1.2 master secret or TLS 1.3 resumption PSK. A custom session store that logs these values can disclose keys to readers of the logs. Ordinary connection and built-in cache diagnostics remain redacted, and the session-store interface already warns that its values are sensitive.
Details
Derived formatters traverse the session's secret-bearing fields. This conflicts with the project's explicit key-material redaction policy.
Proof of concept
Custom ClientSessionStore implementations could leak secret data by using the provided Tls12ClientSessionValue or Tls13ClientSessionValue in a way that triggers its implementation of the Debug trait.
Impact
Such store implementations could leak the master secret for the TLS connection.
Acknowledgement
Thanks to OpenAI OutboundDisclosures@openai.com for the disclosure.
- Record
GHSA-c8m5-c952-6cm4- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N - Weakness
- CWE-212
- Updated
- 2026-11-08
OSVRUSTSEC-2026-0346
`Debug` impls for client session values expose TLS secrets
The Debug implementations of Tls12ClientSessionValue and
Tls13ClientSessionValue were derived, and so included the TLS 1.2 master
secret or TLS 1.3 resumption PSK in their output.
Custom ClientSessionStore implementations that format these values with
Debug (for example, when logging) could disclose these secrets to readers of
the logs. This conflicts with rustls's
key-material redaction policy.
Ordinary connection and built-in session cache Debug output is redacted and
is not affected.
- Record
RUSTSEC-2026-0346- CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N - Updated
- 2026-11-08
OSVUBUNTU-CVE-2026-123609
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
UBUNTU-CVE-2026-123609- CVSS 4.0
- 4.1 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N - CVSS 3.1
- 4.0 Medium
CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N - Updated
- 2026-11-10
OSVAZL-113167No score
CVE-2026-123609 affecting package kata-containers 4.1.0.kata1-2
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
AZL-113167- Updated
- 2026-11-11
OSVAZL-113185No score
CVE-2026-123609 affecting package kata-containers-cc 3.15.0.aks0-23
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
AZL-113185- Updated
- 2026-11-11
OSVAZL-113272No score
CVE-2026-123609 affecting package rust 1.75.0-31
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
AZL-113272- Updated
- 2026-11-11
OSVAZL-113287No score
CVE-2026-123609 affecting package rust 1.98.1-1
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
AZL-113287- Updated
- 2026-11-11
OSVAZL-113308No score
CVE-2026-123609 affecting package rust-afterburn 5.8.2-2
Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.
- Record
AZL-113308- Updated
- 2026-11-11
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
rustlscrates.io | before 0.23.46 | 0.23.46 |
rustlscrates.io | 0.24.0-dev.1 up to 0.24.0-dev.2 | 0.24.0-dev.2 |
kata-containersAzure Linux:3 | through 4.1.0.kata1-2 | None known |
kata-containers-ccAzure Linux:3 | through 3.15.0.aks0-23 | None known |
rustAzure Linux:3 | through 1.75.0-31 | None known |
rustAzure Linux:3 | 1.85.0 to 1.98.1-1 | None known |
rust-afterburnAzure Linux:3 | through 5.8.2-2 | None known |
rust-rustlsDebian:12 | All versions, plus listed versions 0.20.8-40.20.8-4.10.20.8-4.20.21.10-10.21.12-1 Show 45 moreShow less0.21.12-20.21.12-30.21.12-40.21.12-50.21.12-60.21.12-70.21.12-80.21.12-90.21.5-10.21.5-20.21.5-30.21.5-40.21.5-50.21.6-10.21.6-20.21.6-30.21.6-40.21.7-10.21.8-10.21.8-20.21.8-30.21.8-3.10.21.9-10.23.16-10.23.20+ds-10.23.20+ds-100.23.20+ds-20.23.20+ds-30.23.20+ds-40.23.20+ds-50.23.20+ds-60.23.20+ds-70.23.20+ds-80.23.20+ds-90.23.25+ds-10.23.26+ds-10.23.31+ds-10.23.31+ds-20.23.31+ds-30.23.31+ds-40.23.31+ds-50.23.31+ds-60.23.31+ds-70.23.32+ds-10.23.32+ds-2 | None known |
rust-rustlsDebian:13 | All versions, plus listed versions 0.23.26+ds-10.23.31+ds-10.23.31+ds-20.23.31+ds-30.23.31+ds-4 Show 20 moreShow less0.23.31+ds-50.23.31+ds-60.23.31+ds-70.23.32+ds-10.23.32+ds-20.23.33+ds-10.23.33+ds-20.23.33+ds-30.23.33+ds-40.23.35+ds-10.23.36+ds-10.23.37+ds-10.23.37+ds-20.23.37+ds-30.23.38+ds-10.23.40+ds-10.23.41+ds-10.23.43+ds-10.23.45+ds-10.23.46+ds-1 | None known |
rust-rustlsDebian:14 | All versions, plus listed versions 0.23.26+ds-10.23.31+ds-10.23.31+ds-20.23.31+ds-30.23.31+ds-4 Show 20 moreShow less0.23.31+ds-50.23.31+ds-60.23.31+ds-70.23.32+ds-10.23.32+ds-20.23.33+ds-10.23.33+ds-20.23.33+ds-30.23.33+ds-40.23.35+ds-10.23.36+ds-10.23.37+ds-10.23.37+ds-20.23.37+ds-30.23.38+ds-10.23.40+ds-10.23.41+ds-10.23.43+ds-10.23.45+ds-10.23.46+ds-1 | None known |
Show 4 moreShow less
| Package | Affected | Fixed |
|---|---|---|
rustlscrates.io | 0.21.0 up to 0.23.46 | 0.23.46 |
rust-rustlsUbuntu:24.04:LTS | All versions, plus listed versions 0.21.6-30.21.7-10.21.9-10.21.10-1 | None known |
rust-rustlsUbuntu:26.10 | All versions, plus listed versions 0.23.36+ds-10.23.41+ds-1 | None known |
rust-rustlsUbuntu:26.04:LTS | All versions, plus listed versions 0.23.26+ds-10.23.33+ds-3build20.23.35+ds-10.23.35+ds-1build10.23.36+ds-1 | None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, aliases, references | NVD, OSV | |
| affected, aliases, references | OSV | |
| affected, aliases, facts, published, references | OSV | |
| affected, aliases, references | NVD, OSV | |
| published | EUVD | |
| published | EUVD | |
| aliases, references | GitHub Advisories | |
| aliases, products, published | EUVD | |
| first indexed | CVE List | |
| first indexed | GitHub Advisories, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-123609 is a medium vulnerability (CVSS 4.1) in Rustls, published October 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.10%, the 0th percentile. Fixed in rustls 0.23.46.
References
github.com/rustls/rustls/security/advisories/GHSA-c8m5-c952-6cm4
vulncheck.com/advisories/rustls-before-0.23.46-and-0.24.0-dev.1-before-0.24.0-dev.2-secret-exposure-via-debug
nvd.nist.gov/vuln/detail/CVE-2026-123609
Show 11 moreShow less
rustsec.org/advisories/RUSTSEC-2026-0346.html
security-tracker.debian.org/tracker/CVE-2026-123609
crates.io/crates/rustls
ubuntu.com/security/CVE-2026-123609
cve.org/CVERecord?id=CVE-2026-123609
Left out here: 15 versions. The JSON record has them.