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CVE-2026-25541

HIGHCVSS 7.5/10EPSS 0.56%

Last modified

CVE-2026-25541 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 0.56% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS 4.0
5.5/10

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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.56%

42.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
Tokio-RsBytes>= 1.2.1, < 1.11.1

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-25541?
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.
How severe is CVE-2026-25541?
CVE-2026-25541 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 0.56% probability of exploitation in the next 30 days.
How do I fix CVE-2026-25541?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST