# CVE-2023-46218: curl cookie mixed case PSL bypass

Source: https://junglewise.ai/threats/cve-2023-46218-curl-cookie-mixed-case-psl-bypass  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2023-12-07. Updated: 2026-05-12  
License: CC BY 4.0 with a link back

CVE-2023-46218 · Severity: medium · CVSS 6.5 · Published 2023-12-07

A vulnerability in the curl data transfer tool allows malicious websites to set "super cookies" that are shared with unrelated domains. This could allow an attacker to track users or interfere with sessions on different websites. The issue stems from how curl handles uppercase and lowercase letters when checking domain names against a security list.

Technologies: [Fedoraproject Fedora](https://junglewise.ai/threats/technologies/fedora), [Haxx Curl](https://junglewise.ai/threats/technologies/curl). Vendors: [Fedoraproject](https://junglewise.ai/threats/vendors/fedoraproject), [Haxx](https://junglewise.ai/threats/vendors/haxx).

## Quick answers

**Is CVE-2023-46218 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2023-46218 being exploited in the wild.

**How severe is CVE-2023-46218?** Medium severity, with a CVSS score of 6.5, published 7 December 2023.

**Which products and versions are affected?** curl curl 7.46.0 to 8.4.0.

**Is there a fix for CVE-2023-46218?** A patch was published on 2023-12-06: curl 8.5.0 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2023-46218 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2023-46218?** Check whether you run Fedoraproject Fedora or Haxx Curl. 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 flaw exists in curl's cookie domain verification logic when comparing domains against the Public Suffix List (PSL). The function fails to properly normalize case sensitivity, allowing a server to set a cookie for a domain like 'co.UK' even if 'co.uk' is a protected public suffix. This bypass enables the creation of "super cookies" that are subsequently sent to unrelated origins. The vulnerability affects curl versions 7.46.0 through 8.4.0 when built with PSL support. A fix was introduced in version 8.5.0 by converting both strings to lowercase before performing the PSL check.

## Affected products

- curl curl 7.46.0 to 8.4.0

## Timeline

- 2023-10-16: disclosed: Issue reported to the curl project
- 2023-11-28: other: Contacted distributions via openwall
- 2023-12-06: patched: curl 8.5.0 released with fix
- 2023-12-06: advisory: Project curl security advisory published

## References

- [https://curl.se/docs/CVE-2023-46218.html](https://curl.se/docs/CVE-2023-46218.html)
- [https://hackerone.com/reports/2212193](https://hackerone.com/reports/2212193)
- [https://lists.debian.org/debian-lts-announce/2023/12/msg00015.html](https://lists.debian.org/debian-lts-announce/2023/12/msg00015.html)
- [https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3ZX3VW67N4ACRAPMV2QS2LVYGD7H2MVE/](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/3ZX3VW67N4ACRAPMV2QS2LVYGD7H2MVE/)
- [https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UOGXU25FMMT2X6UUITQ7EZZYMJ42YWWD/](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/UOGXU25FMMT2X6UUITQ7EZZYMJ42YWWD/)
- [https://security.netapp.com/advisory/ntap-20240125-0007/](https://security.netapp.com/advisory/ntap-20240125-0007/)
- [https://www.debian.org/security/2023/dsa-5587](https://www.debian.org/security/2023/dsa-5587)

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