Vulnerability · RUSTSEC-2026-0337
Poly1305 panics or computes a wrong tag on attacker-chosen messages of 64 bytes or more
Published Oct 9, 2026 · RustSec Rust · evidence confidence high
in absorbs messages of 64 bytes or more four blocks at a time, summing four products before one reduction. From 0.2.5 to 0.2.19 the reduction kept its carries in 32-bit integers, which four summed products can overflow when the message's bytes are large. This affects and , and everything built on them: the TLS and QUIC ChaCha20-Poly1305 suites in , HPKE with that cipher in , and the re-exports in and . What happens depends on how the crate was compiled: - With overflow checks on (any debug build, or a release profile with ) the multiplication panics, and under the process ends. The tag is comp
Grounded briefings
Catalog interpretations for three audiences. Each brief cites ingested metadata and the original advisories below. They are not independent research and they do not invent exploit steps.
Executive
RUSTSEC-2026-0337 is a unknown public vulnerability record for RustSec Rust. It is not currently listed in the CISA Known Exploited catalog. Check the linked vendor or CERT advisories for patch status. This summary is a catalog interpretation of the ingested metadata and cites the original advisories below.
System administrator
Identify whether RustSec Rust is in your estate, then compare installed versions with the affected ranges. Affected version ranges have not been ingested yet. Check the linked vendor or CERT advisories for patch status. Prefer the vendor or distribution advisory linked in Sources before changing production systems. This is a catalog interpretation, not a runbook.
Security analyst
Signals on file: no CVSS/EPSS yet. It is not currently listed in the CISA Known Exploited catalog. Sources contributing to this record: rustsec. Public exploit references, when present, are outbound links only and are not proof of active exploitation. This is a catalog interpretation of stored metadata.
Exploitation and remediation
Exploitation evidence
Not listed as known exploited in CISA KEV. Not in CISA KEV or VulnCheck KEV.
Patch and remediation
No required-action text is stored yet. Use the vendor or CERT links in Sources for patch availability.
Safe detection guidance
Compare installed versions with the affected ranges below and verify the advisory from the original publisher. This site stores metadata and outbound links only; it does not ship exploit code or proof-of-concept payloads.
Code
The project this record applies to. Exploit listings stay in References.
No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Oct 9, 2026 · RustSec Advisory DB
Detected
in absorbs messages of 64 bytes or more four blocks at a time, summing four products before one reduction. From 0.2.5 to 0.2.19 the reduction kept its carries in 32-bit integers, which four summed products can overflow when the message's bytes are large. This affects and , and everything built on them: the TLS and QUIC ChaCha20-Poly1305 suites in , HPKE with that cipher in , and the re-exports in
Sources
- RustSec Advisory DBVendor advisoryRUSTSEC-2026-0337
in absorbs messages of 64 bytes or more four blocks at a time, summing four products before one reduction. From 0.2.5 to 0.2.19 the reduction kept its carries in 32-bit integers, which four summed products can overflow when the message's bytes are large. This affects and , and ev
crates.io