# CVE-2026-121261: phpMyAdmin ShapeFile infinite loop in SHP file parsing

Source: https://junglewise.ai/threats/cve-2026-121261-a-vulnerability-has-been-found-in-phpmyadmin-shapefile-up-to-4-0  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-03. Updated: 2026-11-03  
License: CC BY 4.0 with a link back

CVE-2026-121261 · Severity: medium · CVSS 4.3 · Published 2026-11-03

phpMyAdmin ShapeFile is a library for reading ESRI shapefile data, commonly used in database management tools. A malformed shapefile with truncated content can cause the parser to enter an infinite loop, consuming 100% of a CPU core indefinitely. An attacker who can upload or supply a crafted shapefile through any application using this library can trigger a denial-of-service condition with minimal effort—a 112-byte file is sufficient.

Vendors: [phpMyAdmin](https://junglewise.ai/threats/vendors/phpmyadmin).

## Quick answers

**Is CVE-2026-121261 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-121261 being exploited in the wild.

**How severe is CVE-2026-121261?** Medium severity, with a CVSS score of 4.3, published 3 November 2026.

**Which products and versions are affected?** phpMyAdmin ShapeFile up to 4.0.1.

**Is there a fix for CVE-2026-121261?** 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-2026-121261 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-121261?** Check whether you run phpMyAdmin ShapeFile 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

The ShapeRecord::loadFromFile method contains an infinite loop when parsing a .shp record whose declared content length exceeds the actual bytes remaining in the file. The vulnerability exists because readSHP() returns an empty string at EOF rather than false, so strlen("") = 0 means the loop counter never advances, creating an unreachable exit condition (CWE-835). Remote attackers can trigger this without authentication by uploading or providing a malformed shapefile to any application that calls ShapeFile::loadFromFile().

## Affected products

- phpMyAdmin ShapeFile up to 4.0.1

## Timeline

- 2026-11-03: disclosed: Public disclosure; exploit available
- 2026-10-07: other: Vulnerability identified and reproducer generated

## References

- [https://gist.github.com/Ishanoshada/efbda3b5bee92058cc6b08f67d4e7363](https://gist.github.com/Ishanoshada/efbda3b5bee92058cc6b08f67d4e7363)
- [https://vuldb.com/cve/CVE-2026-121261](https://vuldb.com/cve/CVE-2026-121261)