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CVE-2026-25541RUSTSEC-2026-0007GHSA-434X-W66G-QW3R

Bytes is vulnerable to integer overflow in BytesMut::reserve

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.11.1
1 proof of concept on GitHub
  • Exploitation: poc
  • Automatable: no
  • Technical impact: partial

Summary

Bytes is a utility library for working with bytes. From version 1.2.1 to before 1.11.1, Bytes is vulnerable to integer overflow in BytesMut::reserve. In the unique reclaim path of BytesMut::reserve, if the condition "v_capacity >= new_cap + offset" uses an unchecked addition. When new_cap + offset overflows usize in release builds, this condition may incorrectly pass, causing self.cap to be set to a value that exceeds the actual allocated capacity. Subsequent APIs such as spare_capacity_mut() then trust this corrupted cap value and may create out-of-bounds slices, leading to UB. This behavior is observable in release builds (integer overflow wraps), whereas debug builds panic due to overflow checks. This issue has been patched in version 1.11.1.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: poc · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • tokio-rs bytes

    From 1.2.1 · fixed in 1.11.1

  • bytescrates.io

    From 1.2.1 · fixed in 1.11.1

References 5

GitHub · tokio-rs/bytes

rustsec.org

GitHub · trajanOx/cve-2026-25541-fuel-analysis