# CVE-2026-5773: wrong reuse of SMB connection

> libcurl may reuse incorrect SMB connections, causing downloads of wrong files or uploads to wrong locations due to logical errors in connection pooling.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:** 13 May 2026
- **Updated:** 15 Sep 2026
- **Also known as:** ALPINE-CVE-2026-5773, BELL-CVE-2026-5773, CLSA-2026-1779098432, CLSA-2026-1779357116, CLSA-2026-1779357393, CLSA-2026-1779357606, CLSA-2026-1779357791, CLSA-2026-1779358008, CLSA-2026-1779358120, CURL-CVE-2026-5773, DEBIAN-CVE-2026-5773, ECHO-73da-59b1-befa, GHSA-rp9q-8q5w-ch44, JLSEC-2026-1205, MINI-h4jq-xcr6-grr6, MINI-rpcf-hgm3-fwch, ROOT-OS-ALPINE-315-CVE-2026-5773, ROOT-OS-ALPINE-320-CVE-2026-5773, ROOT-OS-ALPINE-321-CVE-2026-5773, ROOT-OS-ALPINE-322-CVE-2026-5773, ROOT-OS-DEBIAN-11-CVE-2026-5773, ROOT-OS-DEBIAN-12-CVE-2026-5773, UBUNTU-CVE-2026-5773

## What is CVE-2026-5773?

CVE-2026-5773 is a high-severity vulnerability in Haxx Curl, published on 13 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

libcurl might in some circumstances reuse the wrong connection for SMB(S)
transfers.

libcurl features a pool of recent connections so that subsequent requests can
reuse an existing connection to avoid overhead.

When reusing a connection a range of criteria must be met. Due to a logical
error in the code, a network transfer operation that was requested by an
application could wrongfully reuse an existing SMB connection to the same
server that was using a different "share" than the new subsequent transfer
should.

This could in unlucky situations lead to the download of the wrong file or the
upload of a file to the wrong place. When this happens, the same credentials
are used and the server name is the same.

Weakness: CWE-918 (Server-Side Request Forgery), CWE-488 (Exposure of Data Element to Wrong Session)

## Which versions are affected by CVE-2026-5773?

It affects 1 product.


Products: Haxx Curl.

## How do I fix CVE-2026-5773?

Upgrade to a fixed version.

## Is CVE-2026-5773 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-5773 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-2026-5773 and fix it if it is affected.

What it is: CVE-2026-5773 is a high-severity vulnerability in Haxx Curl, published on 13 May 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-2026-5773 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-2026-5773/ (Markdown: https://insights.sbomify.com/CVE-2026-5773/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5773
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5773
- OSV: https://osv.dev/vulnerability/CVE-2026-5773

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5773/
Summaries are generated and may contain mistakes; the official description above is the record.