Rust advisories / dcrypt-symmetric
VulnerabilityRUSTSEC-2026-0239 · dcrypt-symmetric
RUSTSEC-2026-0239: Streaming AEAD does not authenticate stream structure
Short answerA security vulnerability in the dcrypt-symmetric crate: Streaming AEAD does not authenticate stream structure. No severity score was published. Fixed in 2.0.0: update to a fixed version.
| Crate | dcrypt-symmetric |
|---|---|
| Type | Vulnerability (crypto-failure, denial-of-service) |
| Affected versions | Before 2.0.0. |
| Fixed in | 2.0.0 |
| Severity | not scored |
| Published | 2026-08-09 |
| Last changed | 2026-10-12 |
| Also known as | GHSA-8cwp-4826-jg9f |
What to do
- See which version you have:
cargo tree -i dcrypt-symmetric(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p dcrypt-symmetric. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for exampledcrypt-symmetric = "2.0.0") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
In all published versions of dcrypt-symmetric before 2.0.0, version-1 GCM and ChaCha20-Poly1305 streams used unauthenticated terminator, counter, and length fields. Decryptors trusted transmitted counters, allocated from unbounded lengths, and discarded plaintext that did not fit a caller's single read buffer. An attacker could obtain successful truncated EOF, omit, replay, or reorder frames within a stream, or request an allocation approaching 4 GiB.
Version 2.0.0 introduces the DCRSTRM2 format, which authenticates its version, algorithm, random stream identifier, base nonce, strict sequence, bounded lengths, final flag, and caller AAD. It enforces authenticated finality and physical EOF, bounds frames to 16 KiB before allocation, retains partial-read plaintext, and rejects legacy version-1 input. Existing version-1 ciphertext cannot retrospectively prove completeness or ordering and must be migrated only through an application-specific, explicitly trusted process.
References
- Package: crates.io/crates/dcrypt-symmetric
- Advisory: rustsec.org/advisories/RUSTSEC-2026-0239.html
- Web: github.com/ioi-foundation/dcrypt/commit/c99cc86f0ee353010cd202cbcd2c310371b0bbb8
- Web: github.com/ioi-foundation/dcrypt/commit/c99cc86f0ee353010cd202cbcd2c310371b0bbb8
- Web: github.com/ioi-foundation/dcrypt/releases/tag/v2.0.0
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
Up next
Are you affected?Check your whole dependency treePaste Cargo.lock: every advisory, for your exact versions.Read it next →Also worth your time
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