Skip to content

Conversation

@oxide-renovate
Copy link

@oxide-renovate oxide-renovate bot commented Feb 3, 2026

This PR contains the following updates:

Package Type Update Change
bytes workspace.dependencies minor 1.10.1 -> 1.11.1

GitHub Vulnerability Alerts

CVE-2026-25541

Details

In the unique reclaim path of BytesMut::reserve, the condition

if 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.

PoC

use bytes::*;

fn main() {
    let mut a = BytesMut::from(&b"hello world"[..]);
    let mut b = a.split_off(5);

    // Ensure b becomes the unique owner of the backing storage
    drop(a);

    // Trigger overflow in new_cap + offset inside reserve
    b.reserve(usize::MAX - 6);

    // This call relies on the corrupted cap and may cause UB & HBO
    b.put_u8(b'h');
}

Workarounds

Users of BytesMut::reserve are only affected if integer overflow checks are configured to wrap. When integer overflow is configured to panic, this issue does not apply.


Release Notes

tokio-rs/bytes (bytes)

v1.11.1

Compare Source

  • Fix integer overflow in BytesMut::reserve

v1.11.0

Compare Source

Fixed
  • fix: BytesMut only reuse if src has remaining (#​803)
  • Specialize BytesMut::put::<Bytes> (#​793)
  • Reserve capacity in BytesMut::put (#​794)
  • Change BytesMut::remaining_mut to use isize::MAX instead of usize::MAX (#​795)
Internal changes
  • Guarantee address in slice() for empty slices. (#​780)
  • Rename Vtable::to_* -> Vtable::into_* (#​776)
  • Fix latest clippy warnings (#​787)
  • Ignore BytesMut::freeze doctest on wasm (#​790)
  • Move drop_fn of from_owner into vtable (#​801)

Configuration

📅 Schedule: Branch creation - "" in timezone America/Los_Angeles, Automerge - "after 8pm,before 6am" in timezone America/Los_Angeles.

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.


  • If you want to rebase/retry this PR, check this box

This PR has been generated by Renovate Bot.

@oxide-renovate oxide-renovate bot added the dependencies Pull requests that update a dependency file label Feb 3, 2026
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

dependencies Pull requests that update a dependency file

Projects

None yet

Development

Successfully merging this pull request may close these issues.

0 participants