CVE-2026-115693
Custom cacerts or cacertfile do not restrict trust to the pinned CA in hackney
- Published
- Updated
- Reserved
- Assigned by
- EEF
Description
Improper Certificate Validation vulnerability in hackney_ssl in benoitc hackney allows an on-path attacker to impersonate a server pinned to a private certificate authority via a certificate chain that ends in a publicly trusted root. hackney adds {partial_chain, fun hackney_ssl:partial_chain/1} to every verify_peer configuration. The callback returns any certificate in the peer chain whose public key matches a root in the bundled certifi store as the trust anchor, and OTP honours that callback over the configured cacerts. hackney_ssl:merge_ssl_opts/3 kept the callback when the caller replaced the trust store with cacerts or cacertfile in ssl_options, so a connection pinned to a private CA still accepted any chain that carried a publicly trusted root. The hostname check still applies, so the attacker needs a publicly trusted certificate for the pinned hostname. This issue affects hackney: from 1.24.0 before 4.9.0.
Timeline
ID reserved
By EEF
- 1 day later
· 1 day later
Published
- 7 days later
· 7 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| EEFCNA (assigner) | 4.0 | Critical9.1 | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N |
| NVDNVD · Awaiting Analysis | 4.0 | Critical9.1 | CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
- EPSS (exploitation in 30 days)
- 0.27% · top 81% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: Critical 9.1.
Weakness
Affected products
What to do
Workaround: Pass your own {partial_chain, Fun} in ssl_options alongside cacerts or cacertfile. A caller-supplied partial_chain replaces hackney's in the merge, and a callback that returns unknown_ca makes OTP validate against the configured cacerts only.
References (6)
- Drop the certifi partial_chain when the caller pins cacerts or cacertfile (benoitc/hackney#978) (opens in a new tab)related
- EEF CNA record for CVE-2026-115693 (opens in a new tab)related
- OSV record EEF-CVE-2026-115693 (opens in a new tab)related
- hackney 4.9.0 release notes (opens in a new tab)vendor-advisoryrelated
- Introducing commit d8a9afc in benoitc/hackney (opens in a new tab)related
- Fix commit 915eb57 in benoitc/hackney (opens in a new tab)patch
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-115693)Record last updated .