CVE-2026-54417: rxi microtar integer overflow in mtar_next

CVE-2026-54417 · Severity: high · CVSS 7.5 · Published 2026-06-17

rxi microtar is a lightweight C library used for reading and writing tar archives. A flaw in how the library calculates file positions allows a specially crafted archive to trigger an infinite loop. This can cause applications using the library to hang and consume 100% of the CPU, leading to a total denial of service.

Technologies: Rxi Microtar. Vendors: Rxi.

Quick answers

Is CVE-2026-54417 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-54417 being exploited in the wild.
How severe is CVE-2026-54417?
High severity, with a CVSS score of 7.5, published 17 June 2026.
Which products and versions are affected?
Rxi Microtar 0.1.0.
Is there a fix for CVE-2026-54417?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-54417 attacked?
It is attacked over the network, in a software library.
Am I affected by CVE-2026-54417?
Check whether you run Rxi Microtar 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

An integer overflow exists in the mtar_next() function within src/microtar.c of rxi microtar 0.1.0. The function calculates the offset to the next record using 32-bit arithmetic: round_up(h.size, 512) + sizeof(mtar_raw_header_t). If a crafted tar header specifies a size that, when rounded and added to the header size, results in a 32-bit integer wrap-around to zero (specifically sizes in the range 0xFFFFFC01-0xFFFFFE00), the library seeks to the current record position instead of advancing. This causes mtar_find() or any iteration loop to repeat indefinitely, resulting in 100% CPU consumption and a process hang. The vulnerability can be triggered by any application that parses untrusted tar files using this library.

Affected products

  • rxi microtar 0.1.0

Timeline

  • 2026-06-17: advisory: NVD publication date

References

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