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CVE-2026-59993
Picotls has NULL pointer dereference during handshake, when running as a client
Medium6.5EPSS 0.25%
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
Description
Picotls is a TLS protocol library that allows users select different crypto backends based on their use case. In affected revisions through 44bc503, when picotls is used as a `client-side TLS stack`, a peer can send a `HelloRetryRequest` followed by a `spoofed Hello message` that causes a null-pointer dereference. This can terminate the consuming process, including a process performing other work, resulting in denial of service. This issue is fixed in commit a06ca41.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H |
| NVDNVD · Deferred | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.25% · top 84% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
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The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Weakness
Affected products
References (3)
- https://github.com/h2o/picotls/security/advisories/GHSA-2xcv-h2pg-m99c (opens in a new tab)x_refsource_CONFIRM
- https://github.com/h2o/picotls/pull/608 (opens in a new tab)x_refsource_MISC
- https://github.com/h2o/picotls/commit/a06ca417a16f9126808bf5cabe6c5e6e0f16ecae (opens in a new tab)x_refsource_MISC
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)
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[](https://trackcve.app/cve/CVE-2026-59993)Record last updated .