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Fencer Vulns
medium 6.9

CVE-2026-65627 json

Decompression bomb via unbounded zlib:inflate in jose_jwe_zip:uncompress/2

published 2026-10-26 13 d ago modified 2026-11-02 6 d ago also EEF-CVE-2026-65627 , GHSA-wfpv-qxp8-x5gm , EUVD-2026-110306

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 16%
public exploits
0
none known

Summary

Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in potatosalad jose (erlang-jose) allows a remote attacker to exhaust a node's memory with a small crafted JWE token.

The jose_jwe_zip:uncompress/2 function in src/jwe/jose_jwe_zip.erl decompresses the DEFLATE-compressed plaintext of a JWE that carries the optional zip: DEF header by calling zlib:inflate/2 on the entire attacker-controlled stream, with no bound on the output size or the inflation ratio. Raw DEFLATE reaches ratios around 1000:1 on highly repetitive input, so a few-kilobyte token inflates to hundreds of megabytes or gigabytes in a single call.

Decompression runs automatically during decryption through jose_jwe:block_decrypt/2 (JOSE.JWE.block_decrypt/2 in Elixir), before the recipient can inspect or reject the payload. With the common asymmetric key-management algorithms (RSA-OAEP, ECDH-ES) an attacker needs only the recipient's public key to craft such a token, so no authentication or secret material is required. A single small token can exhaust the node's memory and crash the BEAM, denying service to all users.

This issue affects jose: from 1.0.0 before 1.11.13.

Patch / fix

  • hex jose 1.11.13
  • potatosalad jose 1.11.13

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-2026-65627 updated cvss 7.5

jose: jose: Denial of Service via unbounded decompression of crafted JWE tokens

  • Red Hat Hardened Images rabbitmq-server4.2 4.2.9-0.3.hum1
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Hardened Images grafana13.1 13.1.8-0.4.hum1, grafana13.2 13.2.4-0.3.hum1, grafana12.4 12.4.13-0.4.hum1, rabbitmq-server4.3 4.3.7-0.1.hum1, rabbitmq-server4.3 4.3.7-0.2.hum1
    fixed: vendor fix RHSA-2026:90388
  • Red Hat OpenStack Platform 17.1 rabbitmq-server Red Hat OpenStack Platform 18.0 rabbitmq-server
    not affected: vulnerable code not in execute path

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
6 d ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 16% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/potatosalad/erlang-jose/security/advisories/GHSA-wfpv-qxp8-x5gm referenced PoC, tagged "exploit" by a source, unverified

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
>=1.0.0, <1.11.13
1.11.13

Affected products

  • potatosalad jose

Classification

Weakness
  • CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

References

Sources

Fencer Vulns 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.