# stale custom cookie host causes cookie leak

CVE record · `CVE-2026-6276`

- **Identifiers:** `CVE-2026-6276`
- **State:** Confirmed
- **Severity:** CVSS 7.5 High
- **Critical:** No
- **CNA:** curl
- **Weakness (CWE):** [CWE-346](https://cwe.mitre.org/data/definitions/346.html)
- **Tags:** [CWE-346](https://agentprime.io/advisories/tag/cwe-346.md)
- **Technologies:** [curl](https://agentprime.io/advisories/technology/curl.md)
- **Published:** 13 May 2026
- **Updated:** 15 Sept 2026
- **Reviewed by a person:** No

Published by the CVE Program (CNA: curl) at 13 May 2026, 08:28 UTC. agentprime has not analysed this yet, so whether it affects any app is not known. This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it.

## Affected products, as the CNA wrote them

- Vendor: curl. Product: curl.
  - affected: `7.71.0 to before 8.14.2` (semver)
  - affected: `8.15.0 to before 8.16.1` (semver)
  - affected: `8.17.0 to before 8.20.0` (semver)
  - Other versions: unaffected
- Vendor: curl. Product: curl.
  - affected: `e15e51384a423be31318b3c9c7d612a1aae661fd to before 3a19987a87f393d9394fe5acc7643f6c263c92db` (git)
  - Other versions: unaffected
- Vendor: curl. Product: curl.
  - affected: `8.19.0`
  - affected: `8.18.0`
  - affected: `8.17.0`
  - affected: `8.16.0`
  - affected: `8.15.0`
  - affected: `8.14.1`
  - affected: `8.14.0`
  - affected: `8.13.0`
  - affected: `8.12.1`
  - affected: `8.12.0`
  - affected: `8.11.1`
  - affected: `8.11.0`
  - and 41 more
  - Other versions: unaffected

## Not analysed yet

We haven’t published our own analysis of this CVE. If a person reviews it, this page will say what’s affected and what has to be true for it to matter.

## Severity and exploitation

- 7.5 High, CVSS 3.1: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`, from ADP (CISA-ADP)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0029, the 22nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the CVE Program, published 13 May 2026. New records show when each source confirmed them.

## Sources

- [CVE List: CVE-2026-6276](https://www.cve.org/CVERecord?id=CVE-2026-6276)
- [NVD: CVE-2026-6276](https://nvd.nist.gov/vuln/detail/CVE-2026-6276)

### References from the CNA

- <https://curl.se/docs/CVE-2026-6276.json>
- <https://curl.se/docs/CVE-2026-6276.html>
- <https://hackerone.com/reports/3671818>

Facts on this page come from the CVE List as the CNA published them, with CVSS from the sources named above, CISA KEV and FIRST EPSS. Vendors, products and versions are shown as the CNA wrote them. We don’t reproduce the CVE’s description.

## Check whether this affects you

This CVE names a vendor and product rather than a package, so the lockfile check doesn’t match it. Compare the affected versions above with what you run.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), `get_advisory` returns this record and `search_advisories` finds related ones. Setup: <https://agentprime.io/mcp.md>
- As JSON: <https://api.agentprime.io/v1/advisories/CVE-2026-6276>
- Everything that needs attention now: <https://agentprime.io/advisories/critical.md>

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The web page: <https://agentprime.io/advisories/CVE-2026-6276/>. Everything for agents: <https://agentprime.io/llms.txt>.