Is CVE-2026-38640 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-38640 being exploited in the wild.

How severe is CVE-2026-38640?

Informational severity, with a CVSS score of 5.5, published 25 June 2026.

Which products and versions are affected?

Redox OS Relibc commit 61f42d6b93adc552a9e8b6f207fca907e8ca8be2 and earlier.

Is there a fix for CVE-2026-38640?

A patch was published on 2026-02-10: Merge request 986 submitted to fix the issue using to_string_lossy Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-38640 attacked?

It is attacked with local access, in a software library.

Am I affected by CVE-2026-38640?

Check whether you run Redox OS Relibc at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-38640: Redox OS relibc Denial of Service in __assert_fail

CVE-2026-38640 · Severity: info · CVSS 5.5 · Published 2026-06-25

A vulnerability in relibc, a standard C library used by the Redox operating system, can cause applications to crash unexpectedly. By providing specially crafted, non-UTF-8 text to certain system functions, a local user or malicious program can trigger a system panic. This results in a denial-of-service condition where the affected application or service becomes unavailable.

Technologies: Redox OS Relibc. Vendors: Redox OS.

Quick answers

Is CVE-2026-38640 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-38640 being exploited in the wild.
How severe is CVE-2026-38640?: Informational severity, with a CVSS score of 5.5, published 25 June 2026.
Which products and versions are affected?: Redox OS Relibc commit 61f42d6b93adc552a9e8b6f207fca907e8ca8be2 and earlier.
Is there a fix for CVE-2026-38640?: A patch was published on 2026-02-10: Merge request 986 submitted to fix the issue using to_string_lossy Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-38640 attacked?: It is attacked with local access, in a software library.
Am I affected by CVE-2026-38640?: Check whether you run Redox OS Relibc at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A denial of service vulnerability exists in relibc's `__assert_fail` function located in `src/header/assert/mod.rs`. The implementation uses `.to_str().unwrap()` on C-style strings provided as arguments (function name, file name, or condition). If these strings contain invalid UTF-8 sequences (e.g., 0xFF), the Rust `unwrap()` call triggers a panic, crashing the process. An attacker can exploit this by executing a local program that passes malformed strings to `__assert_fail`. A fix has been proposed to use `to_string_lossy()` to safely handle invalid UTF-8 data.

Affected products

Redox OS relibc commit 61f42d6b93adc552a9e8b6f207fca907e8ca8be2 and earlier

Timeline

2026-02-10: patched: Merge request 986 submitted to fix the issue using to_string_lossy
2026-06-25: disclosed: CVE-2026-38640 published

References

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