CVE-2026-25541

Name	CVE-2026-25541
Description	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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
rust-bytes (PTS)	bullseye	0.4.12-1	fixed
	bookworm	1.2.1-1	vulnerable
	trixie	1.9.0-1	vulnerable
	forky, sid	1.11.1-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
rust-bytes	source	bullseye	(not affected)
rust-bytes	source	(unstable)	1.11.1-1

Notes

[trixie] - rust-bytes <no-dsa> (Minor issue)
[bookworm] - rust-bytes <no-dsa> (Minor issue)
[bullseye] - rust-bytes <not-affected> (Vulnerable code was introduced in v1.2.1)
https://rustsec.org/advisories/RUSTSEC-2026-0007.html
https://github.com/advisories/GHSA-434x-w66g-qw3r
Fixed by: https://github.com/tokio-rs/bytes/commit/d0293b0e35838123c51ca5dfdf468ecafee4398f (v1.11.1)
Introduced by: https://github.com/tokio-rs/bytes/commit/d6e1999d978a688625441348a81504ccab669aed (v1.2.1)