CVE-2026-59251
Erlang/OTP X.509 policy tree DoS via crafted cert chain in TLS handshake.
Is CVE-2026-59251 being exploited?
Not confirmed. CVE-2026-59251 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.32% probability of exploitation in the next 30 days.
How severe is CVE-2026-59251?
CVE-2026-59251 is rated High with a CVSS score of 8.7. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-59251?
Yes. A fix has been recorded for CVE-2026-59251. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-59251 affect?
CVE-2026-59251 affects Erlang/OTP versions prior to patched releases (OTP < 29.0.4), public_key library versions prior to 1.21.4 (and older branch patches for 28.5/27.3). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-59251?
Upgrade to patched OTP/public_key releases (e.g., OTP 29.0.4). Restrict untrusted TLS peers until patched.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote unauthenticated attacker can present a crafted X.509 chain to exhaust BEAM schedulers and memory, causing Erlang VM crash/Denial of Service during TLS handshakes.
Patch when possible
- affected>= 1.15 and < *
- affected>= 26.2 and < *
- affected>= 9d1dda7bad5a64b58c10a1554751689e94131a73 and < *
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.