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.
History

Wed, 04 Feb 2026 22:15:00 +0000

Type Values Removed Values Added
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.
Title Bytes is vulnerable to integer overflow in BytesMut::reserve
Weaknesses CWE-680
References
Metrics cvssV4_0

{'score': 5.5, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-02-04T22:03:53.554Z

Reserved: 2026-02-02T19:59:47.375Z

Link: CVE-2026-25541

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-02-04T22:16:00.383

Modified: 2026-02-04T22:16:00.383

Link: CVE-2026-25541

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.