# CVE-2026-80255: secure cookie attribute bypass with tab

CVE-2026-80255 is fixed in 10 products on 1 platform, first by curl 8.18.0-1ubuntu2.7, released September 6, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-80255
- Priority: High
- CVSS: 7.5 (Low)
- EPSS: 0.0048
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 6, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-80255

## Description

A `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of space (ascii code 32) immediately before the `Secure` attribute causes curl to store the cookie without its Secure flag. The cookie might then wrongfully be sent over plaintext HTTP on subsequent requests to the same host.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | curl Debian 14 | 8.22.0-1 | [DEBIAN-CVE-2026-80255](https://patchblox.com/security/data/fix/linux/debian-cve-2026-80255.md) | Sep 19, 2026 |
| Linux | curl Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | curl Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.7 | [curl 8.18.0-1ubuntu2.7](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-curl-8.18.0-1ubuntu2.7.md) | Sep 6, 2026 |
| Linux | curl sles 15.6 | 8.22.0-150600.4.58.1 | [SUSE-SU-2026:5069-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5069-1.md) | Nov 7, 2026 |
| Linux | curl sles 15.7 | 8.22.0-150700.7.33.1 | [SUSE-SU-2026:5068-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5068-1.md) | Nov 7, 2026 |
| Linux | curl-debuginfo Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | curl-debugsource Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | libcurl Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | libcurl-debuginfo Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | libcurl-devel Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | libcurl-minimal Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | libcurl-minimal-debuginfo Fedora 43 | 8.15.0-12.fc43 | [FEDORA-2026-D65DA12723](https://patchblox.com/security/data/fix/linux/fedora-2026-d65da12723.md) | Nov 7, 2026 |
| Linux | libcurl3t64-gnutls Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.7 | [libcurl3t64-gnutls 8.18.0-1ubuntu2.7](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl3t64-gnutls-8.18.0-1ubuntu2.7.md) | Sep 6, 2026 |
| Linux | libcurl4t64 Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.7 | [libcurl4t64 8.18.0-1ubuntu2.7](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl4t64-8.18.0-1ubuntu2.7.md) | Sep 6, 2026 |

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Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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