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Fencer Intel
medium 6.9

CVE-2026-65631 json

erlang-jose RSA JWK parsing attempts to factor an attacker-controlled modulus, enabling CPU-exhaustion denial of service

published 16d ago modified 8d ago also EEF-CVE-2026-65631 , EUVD-2026-110309 , GHSA-3m45-vrpj-xmrq

cvss
6.9
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits
0
none known

Summary

Inefficient Algorithmic Complexity in erlang-jose allows an unauthenticated remote attacker to cause a CPU-exhaustion denial of service by submitting a crafted RSA JSON Web Key.

When an application parses an untrusted JWK through the public jose_jwk:from_binary/1 or jose_jwk:from_map/1 API (or the Elixir wrappers JOSE.JWK.from_binary/1 and JOSE.JWK.from_map/1), an RSA private key that supplies d, e, and n but omits all Chinese Remainder Theorem parameters (p, q, dp, dq, qi) is routed into convert_sfm_to_crt/1, which tries to recover the missing primes by factoring the modulus. The three integers are read straight from the base64url input and are never validated as a real RSA key. When the modulus cannot be split into two factors (for example, when it is itself prime), the search loop convert_sfm_to_crt_find_p/6 performs a modular exponentiation over the attacker-sized modulus on every iteration and never succeeds. A single request of a few hundred bytes forces close to one CPU-second of work before an internal one-second watchdog kills the worker, and a larger modulus raises the cost further. By flooding such requests an attacker can saturate every scheduler and deny service, without credentials, a valid RSA key, or any special configuration.

This issue affects jose: from 1.7.7 before 1.11.13.

Patch / fix

  • hex jose 1.11.13
  • potatosalad jose 1.11.13
  • erlang-jose Debian 14 1.11.13-1

debian advisories DEBIAN-CVE-2026-65631

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-65631 updated cvss 7.5

jose: jose: Denial of Service via crafted RSA JSON Web Key

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
8d ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 4.0 6.9 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CNA 4.0 6.9 CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/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

Affected packages

ecosystem package affected fixed in
hex jose
>=1.7.7, <1.11.13
1.11.13

Affected products

  • potatosalad jose

Classification

Weakness
  • CWE-407 Inefficient Algorithmic Complexity

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of potatosalad/erlang-jose published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.