# CVE-2026-59251: Erlang OTP denial of service in public_key certificate path validation

Source: https://junglewise.ai/threats/cve-2026-59251-erlang-otp-denial-of-service-in-public-key-certificate-path  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-27. Updated: 2026-07-27  
License: CC BY 4.0 with a link back

CVE-2026-59251 · Severity: info · CVSS 8.7 · Published 2026-07-27

A vulnerability in the Erlang/OTP public_key library can allow a remote attacker to crash the entire Erlang Virtual Machine (VM). By providing a specially crafted security certificate during a standard encrypted connection (TLS) handshake, an attacker can force the system to exhaust its memory and processing power. This affects any application using Erlang's built-in SSL/TLS capabilities, including web servers and clients, potentially leading to a complete service outage.

## Quick answers

**Is CVE-2026-59251 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-59251 being exploited in the wild.

**How severe is CVE-2026-59251?** Informational severity, with a CVSS score of 8.7, published 27 July 2026.

**Which products and versions are affected?** Erlang OTP 26.2 before 29.0.4, 28.5.0.4, and 27.3.4.15; Erlang public_key 1.15 before 1.21.4, 1.20.3.4, and 1.17.1.5.

**Is there a fix for CVE-2026-59251?** A patch was published on 2026-07-23: Fix committed to repository Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-59251 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-59251?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability exists in the RFC 5280 policy processing logic within Erlang's public_key library, specifically in the pubkey_policy_tree module. When validating an X.509 certificate chain, the functions add_leaves/2 and add_leaf_siblings/2 can cause the policy tree to grow exponentially (O(M^K)) if a chain contains many policies per certificate. An unauthenticated remote attacker can exploit this during a TLS handshake by presenting a crafted certificate chain, leading to BEAM scheduler pinning and memory exhaustion. This is a resource exhaustion vulnerability (CWE-770) similar to historical policy tree DoS issues in OpenSSL. Patches have been released in OTP versions 29.0.4, 28.5.0.4, and 27.3.4.15 which introduce a monotonic node counter to cap tree growth.

## Affected products

- Erlang OTP 26.2 before 29.0.4, 28.5.0.4, and 27.3.4.15
- Erlang public_key 1.15 before 1.21.4, 1.20.3.4, and 1.17.1.5

## Timeline

- 2026-07-16: other: Fix authored
- 2026-07-23: patched: Fix committed to repository
- 2026-07-27: advisory: NVD and CNA advisory published

## References

- [https://github.com/](https://github.com/)
- [https://cna.erlef.org/cves/CVE-2026-59251.html](https://cna.erlef.org/cves/CVE-2026-59251.html)
- [https://github.com/erlang/otp/commit/f04c6bba38de1cf1b1836a7d9a9fbe239bd939e8](https://github.com/erlang/otp/commit/f04c6bba38de1cf1b1836a7d9a9fbe239bd939e8)
- [https://github.com/erlang/otp/commit/f8580fc117098c08165f46c26fd0750c5cfb2a90](https://github.com/erlang/otp/commit/f8580fc117098c08165f46c26fd0750c5cfb2a90)
- [https://github.com/erlang/otp/security/advisories/GHSA-622p-qfh6-c352](https://github.com/erlang/otp/security/advisories/GHSA-622p-qfh6-c352)
- [https://www.erlang.org/doc/system/versions.html](https://www.erlang.org/doc/system/versions.html)