---
title: "CVE-2026-45372\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2026-45372?format=md
keywords: index, follow
---

# CVE-2026-45372

Publication date 29 May 2026

Last updated 26 June 2026

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**9.9 · Critical**

[Score breakdown](https://ubuntu.com/security/CVE-2026-45372?format=md#impact-score)

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## Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS
library. Prior to 0.44.0, when cpp-httplib's server parses an incoming
request, it applies percent-decoding to every header value except Location
and Referer. The validity check (is\_field\_value) is run before decoding, so
encoded %0D%0A passes the check and is then expanded to a literal \r\n byte
pair inside the stored header value. This vulnerability is fixed in 0.44.0.

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| cpp-httplib | 26.04 LTS resolute | Fixed 0.26.0+ds-2ubuntu3+esm1  Ubuntu Pro |
| 25.10 questing | Fixed 0.18.7-1ubuntu0.25.10.2 |
| 24.04 LTS noble | Fixed 0.14.3+ds-1.1ubuntu0.1~esm2  Ubuntu Pro |
| 22.04 LTS jammy | Fixed 0.10.3+ds-1ubuntu0.1~esm2  Ubuntu Pro |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

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## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

9.9 · Critical

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | None |
  | User interaction | None |
  | Scope | Changed |
  | Confidentiality impact | Low |
  | Integrity impact | High |
  | Availability impact | Low |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 9.9 · Critical |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-45372)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-45372)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-45372)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-45372)

### Related Ubuntu Security Notices (USN)

+ [USN-8470-1](https://usn.ubuntu.com/USN-8470-1)
+ cpp-httplib vulnerability
+ 25 June 2026

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-45372>
* <https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xjxg-64p4-vj4m>
* <https://github.com/yhirose/cpp-httplib/commit/fbb031ed8504a0e48d9ca63caecc0614c296f755>