CVE-2026-53426
DoS via atom table exhaustion in MDEx JSON parser.
Is CVE-2026-53426 being exploited?
Not confirmed. CVE-2026-53426 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 0.18% probability of exploitation in the next 30 days.
How severe is CVE-2026-53426?
CVE-2026-53426 is rated High with a CVSS score of 8.2. 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-2026-53426?
Yes. A fix has been recorded for CVE-2026-53426. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-53426 affect?
CVE-2026-53426 affects MDEx <= 0.13.1 (MDEx library for Elixir/Erlang). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-53426?
Upgrade MDEx to >= 0.13.2
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated DoS: crafted JSON mints atoms, exhausts BEAM atom table, crashes Erlang VM.
Immediate action required
- affected>= 0.4.3 and < 0.13.2
- affected>= cbb59a3f792dbc343873adec3466f49c853dc309 and < 00fddf444220a1f1cc0af0a1cab6738804878387
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.