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.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
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.
Which versions are affected by CVE-2026-5773?
It affects 1 product.
Products include 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
Sources
Also known as ALPINE-CVE-2026-5773, BELL-CVE-2026-5773, CLSA-2026-1779098432, CLSA-2026-1779357116, CLSA-2026-1779357393, CLSA-2026-1779357606 and 17 more.