CVE-2026-86409: stale SigV4 headers sent unintended
Affected: curl · Exploitation: possible (1 to 10%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 66% of scored CVEs
DescriptionCVE.org
Setting `CURLOPT_AWS_SIGV4` to NULL but does not disable SigV4 authentication, contrary to expectations and documentation. A subsequent transfer on the same handle still sends an `Authorization: AWS4-HMAC-SHA256` header to whatever URL isset next, leaking state information.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- curl · curlfrom 8.21.0 up to and including 8.21.0; from 8.20.0 up to and including 8.20.0; from 8.19.0 up to and including 8.19.0; from 8.18.0 up to and including 8.18.0; from 8.17.0 up to and including 8.17.0; from 8.16.0 up to and including 8.16.0 and 44 more
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Possible (1 to 10%). EPSS between 1% and 10%.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- curl
- Published
- October 2026
- Bounty reports
- 1 disclosed on HackerOne
Disclosed bug bounty reports about CVE-2026-86409
The reports on HackerOne that name this CVE, with HackerOne's own outcome. Titles and metadata only.
- CVE-2026-86409: stale SigV4 headers sent unintendedcurl · 2026Valid
CoverageNo articles yet
No CyberSIXT article names CVE-2026-86409 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.