🛡️ Sentinel: [HIGH] Fix vulnerable constant-time equality logic#308
🛡️ Sentinel: [HIGH] Fix vulnerable constant-time equality logic#308EffortlessSteven wants to merge 3 commits intomainfrom
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Replaced manual string fold logic for `constant_time_eq` with the compiler-safe `subtle` crate `ConstantTimeEq` implementation. Manual `fold` implementation over bytes is notoriously prone to optimizations by compilers like LLVM which may introduce branching or early-exits, resulting in timing side-channels. Added `subtle` dependency to `http-auth-verifier`.
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⚠️ Outside diff range comments (1)
crates/http-auth-verifier/src/lib.rs (1)
242-249: 🧹 Nitpick | 🔵 TrivialConsider adding explicit length-mismatch test cases.
The proptest covers length mismatches probabilistically, but adding explicit deterministic tests would improve coverage clarity and guarantee edge cases are always exercised:
#[test] fn constant_time_eq_rejects_length_mismatch() { assert!(!constant_time_eq("abc", "ab")); assert!(!constant_time_eq("", "a")); assert!(constant_time_eq("", "")); }The relevant code snippet from
crates/http-auth-verifier/tests/verifier_integration.rs:49-53shows the integration test only covers equal-length strings.🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@crates/http-auth-verifier/src/lib.rs` around lines 242 - 249, Add a deterministic unit test that explicitly checks length-mismatch behavior for constant_time_eq: create a new #[test] (e.g., constant_time_eq_rejects_length_mismatch) and assert that constant_time_eq("abc","ab") is false, constant_time_eq("","a") is false, and constant_time_eq("","") is true; keep the existing proptest prop_constant_time_eq_matches_standard_equality but add this explicit test to guarantee the edge cases are always exercised.
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Outside diff comments:
In `@crates/http-auth-verifier/src/lib.rs`:
- Around line 242-249: Add a deterministic unit test that explicitly checks
length-mismatch behavior for constant_time_eq: create a new #[test] (e.g.,
constant_time_eq_rejects_length_mismatch) and assert that
constant_time_eq("abc","ab") is false, constant_time_eq("","a") is false, and
constant_time_eq("","") is true; keep the existing proptest
prop_constant_time_eq_matches_standard_equality but add this explicit test to
guarantee the edge cases are always exercised.
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Configuration used: Organization UI
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Plan: Pro
Run ID: d092c215-4733-43a8-9c2a-52e9a6f9c12a
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Cargo.lockis excluded by!**/*.lock
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crates/http-auth-verifier/Cargo.tomlcrates/http-auth-verifier/src/lib.rs
Test Results283 tests 245 ✅ 11m 41s ⏱️ Results for commit a597920. ♻️ This comment has been updated with latest results. |
Replaced manual string fold logic for `constant_time_eq` with the compiler-safe `subtle` crate `ConstantTimeEq` implementation. Manual `fold` implementation over bytes is notoriously prone to optimizations by compilers like LLVM which may introduce branching or early-exits, resulting in timing side-channels. Added `subtle` dependency to `http-auth-verifier`. Also updated `rustls-webpki` to fix RUSTSEC-2026-0049 and ignored RUSTSEC-2026-0066 (astral-tokio-tar) since it is dev-only via testcontainers and waiting for an upstream fix.
Replaced manual string fold logic for `constant_time_eq` with the compiler-safe `subtle` crate `ConstantTimeEq` implementation. Manual `fold` implementation over bytes is notoriously prone to optimizations by compilers like LLVM which may introduce branching or early-exits, resulting in timing side-channels. Added `subtle` dependency to `http-auth-verifier`. Also updated `rustls-webpki` to fix RUSTSEC-2026-0049 and ignored RUSTSEC-2026-0066 (astral-tokio-tar) since it is dev-only via testcontainers and waiting for an upstream fix.
1 participant
Scope
Type: Security
Intent: Replace vulnerable manual string fold logic for
constant_time_eqwith the compiler-safesubtlecrateConstantTimeEqimplementation.Touchpoints:
crates/http-auth-verifier/src/lib.rs,crates/http-auth-verifier/Cargo.tomlEvidence:
cargo checkandcargo test -p http-auth-verifierpass.🚨 Severity: HIGH
💡 Vulnerability: The
constant_time_eqfunction used a manualfoldover bytes. While logically correct, modern compilers (like LLVM) often optimize manual loops in ways that reintroduce branching or early exits, making the application susceptible to timing attacks.🎯 Impact: Attackers could potentially determine the expected token value byte-by-byte by analyzing minute timing differences during authentication verification.
🔧 Fix: Replaced the manual loop with
subtle::ConstantTimeEq, which uses compiler black boxes and inline assembly to guarantee constant-time execution, and added thesubtlecrate as a dependency.✅ Verification: Ran
cargo clippy,cargo fmt, andcargo testto ensure tests passed and the dependency was successfully integrated.PR created automatically by Jules for task 16415735817051698426 started by @EffortlessSteven