CVE-2026-86409

CVE-2026-86409

published October 21, 2026

CVSS
—
EPSS
0%
Percentile
15.1
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS
Not scored
CVSS v4.0
Not supplied
EPSS
0.00248 · 15.1th percentile
Published
2026-10-21T00:17Z
References (3)
https://curl.se/docs/CVE-2026-86409.html · 2499f714-1537-4658-8207-48ae4bb9eae9https://curl.se/docs/CVE-2026-86409.json · 2499f714-1537-4658-8207-48ae4bb9eae9https://hackerone.com/reports/3973135 · 2499f714-1537-4658-8207-48ae4bb9eae9
EPSS history
Timeline
  • 22 OCT 03:35Z
    EPSS moved — → 0%
    epss
  • 20 OCT 19:57Z
    stale SigV4 headers sent unintended
    cvelistv5
  • 20 OCT 19:57Z
    stale SigV4 headers sent unintended
    cvelistv5