Vulnerability · Published Oct 23, 2026 · Assigned by EEF
CVE-2026-105963Secret key base exposed in stack trace arguments on wrong-typed Plug.Crypto arguments
Medium 5.1
In plain English
A medium-severity sensitive data in logs in plug from elixir-plug. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities).
Official description
Externally-Generated Error Message Containing Sensitive Information vulnerability in plug_crypto in elixir-plug plug_crypto allows an unauthenticated remote attacker to expose the secret key base through application logs via a wrong-typed argument. Every public function in Plug.Crypto validates argument types in a function-head guard. A failed guard makes the Erlang VM raise FunctionClauseError with the actual argument values in the top stack frame, so the secret key base, a derived key, or the value an API key is compared against lands in that frame. The library's rescue blocks and Plug.Crypto.prune_args_from_stacktrace/1 only reach exceptions raised inside a function body, so they never see a guard failure. Plug.Cowboy and Bandit write the frame to the error log and attach it as crash_reason Logger metadata, which error trackers forward. Two entry points take request data. Plug.Crypto.verify/4 exposes the secret key base when the token is neither a binary nor nil, which Phoenix.Token.verify/4 reaches because it forwards the token unguarded. Plug.Crypto.secure_compare/2 exposes the other operand when one side is not a binary, as happens when a missing request header yields nil. Reading the leaked value needs separate access to the logs or the error tracker, so the request alone does not disclose the secret to the attacker. This issue affects plug: from 1.6.3 before 1.7.0; plug_crypto: from 1.0.0 before 2.2.1.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu:22.04:LTS | sonic-pi | no fix listed | UBUNTU-CVE-2026-105963 |
| Ubuntu:24.04:LTS | sonic-pi | no fix listed | UBUNTU-CVE-2026-105963 |
| Ubuntu:26.04:LTS | sonic-pi | no fix listed | UBUNTU-CVE-2026-105963 |
| Ubuntu:26.10 | sonic-pi | no fix listed | UBUNTU-CVE-2026-105963 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| elixir-plug | plug | 1.6.3 – before 1.7.0 |
| elixir-plug | plug | 56000c33d8a0a2fbac491f8be06b9c5112bc2276 – before * |
| elixir-plug | plug_crypto | 1.0.0 – before 2.2.1 |
| elixir-plug | plug_crypto | 2d078b7b8264c565f0ff71235c515f4f46882dcf – before 981887493dada0fce7003c61861c00dfbb0fc8c5 |
Weakness: CWE-532 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References
- Secret key base exposed in stack trace arguments on wrong-typed Plug.Crypto arguments vendor-advisory, related
- EEF CNA record for CVE-2026-105963 related
- OSV record EEF-CVE-2026-105963 related
- Introducing commit 56000c3 in elixir-plug/plug related
- Fix commit aeaa90e in elixir-plug/plug patch
- Introducing commit 2d078b7 in elixir-plug/plug_crypto related
- Fix commit 9818874 in elixir-plug/plug_crypto patch