# CVE-2026-82209: domain-scoped PSL domain cookie

> Attackers can bypass cookie domain restrictions in libcurl to leak cookies to sibling subdomains when libpsl is enabled.

- **Severity:** High 8.2 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** ALPINE-CVE-2026-82209, AZL-99767, AZL-99783, AZL-99804, AZL-99825, AZL-99852, AZL-99882, BELL-CVE-2026-82209, CURL-CVE-2026-82209, DEBIAN-CVE-2026-82209, ECHO-7268-3d2f-bfcf, GHSA-3hpw-4mfr-9f85, MINI-448j-982p-vm89, MINI-fg58-fw8h-j8r3, ROOT-OS-ALPINE-315-CVE-2026-82209, ROOT-OS-ALPINE-320-CVE-2026-82209, ROOT-OS-ALPINE-321-CVE-2026-82209, ROOT-OS-ALPINE-322-CVE-2026-82209, ROOT-OS-DEBIAN-12-CVE-2026-82209, ROOT-OS-DEBIAN-13-CVE-2026-82209, UBUNTU-CVE-2026-82209

## What is CVE-2026-82209?

CVE-2026-82209 is a high-severity vulnerability in Haxx Curl, published on 6 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

When libpsl support is enabled, libcurl fails to enforce the Public Suffix
List boundary check when processing a `Set-Cookie` header where the `Domain`
attribute explicitly matches an origin host that is itself a public suffix
(e.g., `Domain=co.uk` set by `co.uk`).

Instead of coercing it into a strict host-only cookie, libcurl saves the
cookie with wildcard domain scope (`.co.uk`). Consequently, the cookie is
inappropriately included in subsequent outbound requests or HTTP redirects to
arbitrary sibling subdomains under the same public suffix (e.g.,
`attacker.co.uk`).

Weakness: CWE-201 (Insertion of Sensitive Information Into Sent Data)

## Which versions are affected by CVE-2026-82209?

It affects 1 product.


Products: Haxx Curl.

## How do I fix CVE-2026-82209?

Apply the vendor's patch.

## Is CVE-2026-82209 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82209 exists.

## Other vulnerabilities in Haxx Curl

- [CVE-2026-19931](https://insights.sbomify.com/CVE-2026-19931/): Negotiate ambient user conn reuse (critical 9.8)
- [CVE-2026-10536](https://insights.sbomify.com/CVE-2026-10536/): HTTP/2 stream-dependency tree UAF (critical 9.8)
- [CVE-2026-11856](https://insights.sbomify.com/CVE-2026-11856/): cross-origin Digest auth state leak (critical 9.8)
- [CVE-2026-8925](https://insights.sbomify.com/CVE-2026-8925/): SASL double-free (critical 9.8)
- [CVE-2026-9079](https://insights.sbomify.com/CVE-2026-9079/): stale proxy password leak (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-82209 and fix it if it is affected.

What it is: CVE-2026-82209 is a high-severity vulnerability in Haxx Curl, published on 6 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-82209 exists.

Affected product: Haxx Curl. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-82209/ (Markdown: https://insights.sbomify.com/CVE-2026-82209/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-82209
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-82209
- OSV: https://osv.dev/vulnerability/CVE-2026-82209

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-82209/
Summaries are generated and may contain mistakes; the official description above is the record.