cross-origin reuse of a Negotiate connection
Affects curl 8.21.0 through 8.22.0 when ambient user credentials and Negotiate connections are used. curl rates it Low while CVSS scores it 9.1 Critical. Fixed in 8.23.0.
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- The rating the maker of the software gives it. Shown when it differs from the CVSS level.What do these mean? →
- Low (curl)
- Fix
- Fixed in 8.23.0
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: poc
- Automatable: yes
- Technical impact: total
Summary
When using ambient user credentials, an HTTP request directed to one origin may be dispatched over a connection previously authenticated via Negotiate for a different origin, leaving the request's intended credentials unused.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: poc · Automatable: yes · Technical impact: total
- Record last updated
Affected versions
- curl curl
From 8.22.0 · through 8.22.0; From 8.21.0 · through 8.21.0
References 3
hackerone.com
Questions about CVE-2026-87861
What does this mean?
An HTTP request meant for one origin can be sent over a connection that was previously authenticated via Negotiate for a different origin. The request's intended credentials go unused, which exposes information through the sent data (CWE-201).Source: curl.se, curl.se
Am I affected, and how do I check?
curl 8.21.0 through 8.22.0 is affected when ambient user credentials are used and a connection was previously authenticated via Negotiate for a different origin. To check a installed version, run curl --version and compare the number against 8.21.0 through 8.22.0.Source: curl.se, curl.se
What should I do about it?
Upgrade to curl 8.23.0, which contains the fix. Until then, avoid using ambient user credentials for authentication.Source: curl.se, curl.se
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. CISA's SSVC assessment notes a proof of concept exists. No public exploit code is tracked.Source: cve.now feed data