Microsoft security update for CVE-2026-59251 — azl3 erlang 26.2.5.21-4 on Azure Linux 3.0
🔗 CVE IDs covered (1)
📋 Microsoft's advisory
EchelonGraph does not copy Microsoft's advisory page: its FAQ and remediation text are not shown here. Read the advisory on https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-59251. This page also shows what EchelonGraph holds for CVE-2026-59251, with the description from its CVE record, which the CVE Numbering Authority that assigned the CVE wrote: for a CVE Microsoft assigned, often in the words of Microsoft's own advisory.
🎯 Affected products1
- azl3 erlang 26.2.5.21-4 on Azure Linux 3.0
✅ Updates Microsoft lists: 1 update
1 row: one per KB article or update, update type and fixed build. Their details are on Microsoft's advisory.
| KB article | Update | Fixed build |
|---|---|---|
| — | Security Update | 26.2.5.21-3 |
🧭 EchelonGraph on CVE-2026-59251
- EchelonGraph score
- 7.5 HIGH
- CISA KEV
- Not listed
- Fix status
- A fix is available — apply it.
Description from the CVE record (CVE.org), as published by its numbering authority
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 27.3.4.15, OTP 28.5.0.4, and OTP 29.0.4, corresponding to public_key from 1.15 before 1.17.1.5, 1.20.3.4, and 1.21.4.
Published by Erlang Ecosystem Foundation, the CVE Numbering Authority that assigned CVE-2026-59251, in its CVE record at CVE.org; reused under the CVE Program's Terms of Use (its licence and MITRE's copyright notice are in our Terms of Service).