# CVE-2026-115473: Mongoose heap out-of-bounds read in path validation

Source: https://junglewise.ai/threats/cve-2026-115473-mongoose-is-an-embedded-web-server-and-network-library-prior-to  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-04. Updated: 2026-11-04  
License: CC BY 4.0 with a link back

CVE-2026-115473 · Severity: medium · CVSS 6.5 · Published 2026-11-04

Mongoose is an embedded web server library used in IoT and embedded systems. Prior to version 7.22, an attacker could send specially crafted short path requests to trigger out-of-bounds memory reads in the path validation function. On systems without memory protection, this could expose sensitive adjacent memory or cause crashes, potentially enabling information disclosure or denial of service.

Technologies: [Cesanta Mongoose](https://junglewise.ai/threats/technologies/cesanta-mongoose). Vendors: [Cesanta](https://junglewise.ai/threats/vendors/cesanta).

## Quick answers

**Is CVE-2026-115473 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-115473 being exploited in the wild.

**How severe is CVE-2026-115473?** Medium severity, with a CVSS score of 6.5, published 4 November 2026.

**Which products and versions are affected?** Cesanta Mongoose before 7.22.

**Is there a fix for CVE-2026-115473?** Yes: fixed in 7.22. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-115473 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-115473?** Check whether you run Cesanta Mongoose 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.

## How to fix

- Fixed in 7.22

## Technical details

The mg_path_is_sane() function in src/util.c performed array accesses without proper length validation, reading path.buf[1] without ensuring path.len ≥ 2 and reading s[2] with only 2 bytes remaining in the buffer. Unauthenticated remote requests to mg_http_upload or mg_http_serve_dir with short malformed paths could trigger one-byte heap out-of-bounds reads; on bare-metal or RTOS targets lacking memory protection, the exposed byte could influence path acceptance or disclosure, while instrumented builds could crash.

## Affected products

- Cesanta Mongoose before 7.22

## Timeline

- 2026-11-04: disclosed
- 2026-06-24: patched

## References

- [https://github.com/cesanta/mongoose/commit/b55de8b151d1466a3e41d1f854f22eeb6faa23dc](https://github.com/cesanta/mongoose/commit/b55de8b151d1466a3e41d1f854f22eeb6faa23dc)
- [https://github.com/cesanta/mongoose/releases/tag/7.22](https://github.com/cesanta/mongoose/releases/tag/7.22)

## Related threats

- [Mongoose TCP option parser bounds check vulnerability](https://junglewise.ai/threats/cve-2026-73261-mongoose-is-an-embedded-web-server-and-network-library-prior-to-7)
- [Mongoose TLS certificate parser bounds check in DER parsing](https://junglewise.ai/threats/cve-2026-73260-mongoose-is-an-embedded-web-server-and-network-library-prior-to-7)
- [Mongoose TLS short-record out-of-bounds read](https://junglewise.ai/threats/cve-2026-73252-mongoose-is-an-embedded-web-server-and-network-library-prior-to-7)
- [Mongoose IPv6CP length field bounds check buffer overflow](https://junglewise.ai/threats/cve-2026-63626-mongoose-is-an-embedded-web-server-and-network-library-prior-to-7)
- [Cesanta Mongoose stack-based buffer overflow in MQTT broker](https://junglewise.ai/threats/cve-2026-101003-a-weakness-has-been-identified-in-cesanta-mongoose-up-to-7-21)