CVE-2026-59251
Denial of service via exponential certificate policy tree growth in path validation
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.
INFO
Published Date :
July 27, 2026, 4:18 p.m.
Last Modified :
July 27, 2026, 4:18 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update Erlang/OTP to a fixed version.
- Apply the public_key library patches.
- Validate certificate chain processing logic.
- Limit policy tree growth during validation.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-59251.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-59251 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-59251
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-59251 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-59251 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jul. 27, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/erlang/otp', 'vendor': 'Erlang', 'modules': ['pubkey_policy_tree'], 'product': 'OTP', 'versions': [{'status': 'affected', 'changes': [{'at': '1.21.4', 'status': 'unaffected'}, {'at': '1.20.3.4', 'status': 'unaffected'}, {'at': '1.17.1.5', 'status': 'unaffected'}], 'version': '1.15', 'lessThan': '*', 'versionType': 'otp'}], 'packageURL': 'pkg:otp/public_key?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git', 'packageName': 'public_key', 'programFiles': ['src/pubkey_policy_tree.erl'], 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'pubkey_policy_tree:add_leaves/2'}, {'name': 'pubkey_policy_tree:add_leaf_siblings/2'}]}, {'cpes': ['cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/erlang/otp', 'vendor': 'Erlang', 'modules': ['pubkey_policy_tree'], 'product': 'OTP', 'versions': [{'status': 'affected', 'changes': [{'at': '29.0.4', 'status': 'unaffected'}, {'at': '28.5.0.4', 'status': 'unaffected'}, {'at': '27.3.4.15', 'status': 'unaffected'}], 'version': '26.2', 'lessThan': '*', 'versionType': 'otp'}, {'status': 'affected', 'changes': [{'at': 'f8580fc117098c08165f46c26fd0750c5cfb2a90', 'status': 'unaffected'}, {'at': 'f04c6bba38de1cf1b1836a7d9a9fbe239bd939e8', 'status': 'unaffected'}], 'version': '9d1dda7bad5a64b58c10a1554751689e94131a73', 'lessThan': '*', 'versionType': 'git'}], 'packageURL': 'pkg:github/erlang/otp', 'packageName': 'erlang/otp', 'programFiles': ['lib/public_key/src/pubkey_policy_tree.erl'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'pubkey_policy_tree:add_leaves/2'}, {'name': 'pubkey_policy_tree:add_leaf_siblings/2'}]}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/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 Added CWE CWE-770 Added Reference https://cna.erlef.org/cves/CVE-2026-59251.html Added Reference https://github.com/erlang/otp/commit/f04c6bba38de1cf1b1836a7d9a9fbe239bd939e8 Added Reference https://github.com/erlang/otp/commit/f8580fc117098c08165f46c26fd0750c5cfb2a90 Added Reference https://github.com/erlang/otp/security/advisories/GHSA-622p-qfh6-c352 Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-59251 Added Reference https://www.erlang.org/doc/system/versions.html#order-of-versions