Availability loss via unchecked reserve-capacity addition
Published Feb 4, 2026 · Updated Feb 4, 2026
Integer overflow in Bytes 1.2.1 through 1.11.0 allows local users to trigger undefined behavior through an oversized reserve request. BytesMut::reserve adds new_cap and offset without checking for usize overflow, then records a capacity larger than the allocation and lets later APIs create out-of-bounds slices. Exploitation requires a release build with wrapping overflow and control of a reserve size; published impact is limited to consuming-software availability.
Summary
What happened
Integer overflow in Bytes 1.2.1 through 1.11.0 allows local users to trigger undefined behavior through an oversized reserve request. BytesMut::reserve adds new_cap and offset without checking for usize overflow, then records a capacity larger than the allocation and lets later APIs create out-of-bounds slices. Exploitation requires a release build with wrapping overflow and control of a reserve size; published impact is limited to consuming-software availability.
The record
- CVE
- CVE-2026-25541
- Published
- Feb 4, 2026
- Updated
- Feb 4, 2026
- Vendor
- Tokio
- Product
- Bytes
- Classifications
- CWE-680, T1499
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 4, 2026CVE publishedPublication date reported by the CVE source.
- Feb 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 1.2.1, < 1.11.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GitHub advisory BytesMut::reserve proof of conceptproof of concept · unverified
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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