SEPTEMBER 17, 2026
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Case File

CVE-2026-59251

HIGH · CVSS 7.5 EPSS 0.32% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-07-27 · Last synced 2026-08-26

CyberRota Analysis

AI-Generated

The vulnerability in OpenSSL's public_key certificate path validation allows remote unauthenticated attackers to exploit the TLS handshake process by sending a specially crafted X.509 certificate chain, leading to a denial of service due to unbounded resource allocation. This can result in the exhaustion of memory and the crashing of the entire Erlang VM, affecting any system that validates peer certificate chains during TLS connections. Organizations using affected versions of Erlang/OTP (from 26.2 to 29.0.4 and specific versions of OTP 28 and 27) should prioritize patching to mitigate this risk.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

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CVE
CVE-2026-59251
Severity
HIGH
CVSS
7.5
EPSS
0.32%
OpenSSL

Original NVD Description

Allocation of resources without limits in Erlang/OTP public_key certificate path validation allows a remote unauthenticated attacker to cause denial of service by sending a crafted X.509 certificate chain during the TLS handshake. During RFC 5280 policy processing in public_key:pkix_path_validation/3, the certificate policy tree maintained by pubkey_policy_tree grows without an upper bound. When a certificate chain contains M policies per certificate and K certificates, the tree grows on the order of M^K nodes because pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2 extend the tree per policy per certificate. A modest chain with many policies per certificate is enough to pin BEAM schedulers and exhaust the node's memory, taking down the entire VM. The attacker only needs to be able to present a certificate chain to the victim, which is the normal precondition for a TLS handshake, so exploitation succeeds against any incoming or outgoing TLS connection that validates the peer's chain (the default for SSL/TLS clients and mutual-TLS servers). This is the same vulnerability class as OpenSSL's X509_verify_cert policy tree DoS. This vulnerability is associated with program files lib/public_key/src/pubkey_policy_tree.erl and program routines pubkey_policy_tree:add_leaves/2 and pubkey_policy_tree:add_leaf_siblings/2. This issue affects OTP from OTP 26.2 before OTP 29.0.4, OTP 28.5.0.4 and OTP 27.3.4.15, corresponding to public_key from 1.15 before 1.21.4, 1.20.3.4 and 1.17.1.5.

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