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Fencer Intel
critical 9.1

CVE-2026-53939 json

OpenIDC/cjose uses all-zero Content Encryption Key for AES-CBC-HMAC JWE encryption

published 5mo ago modified 2mo ago also EUVD-2026-74299 , GHSA-f6wf-pqg3-6wqq

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository OpenIDC/cjose. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
9.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits
0
none known

Summary

OpenIDC/cjose is a C library implementing the Javascript Object Signing and Encryption (JOSE). In versions 0.6.1 through 0.6.2.5, when cjose encrypts a JWE using an AES-CBC-HMAC content-encryption algorithm (`A128CBC-HS256`, `A192CBC-HS384`, or `A256CBC-HS512`) together with any key-management algorithm that generates a fresh content-encryption key (CEK), the CEK is all zero bytes instead of being randomly generated. The resulting JWE is therefore encrypted and authenticated under a fixed, publicly known key, so anyone who obtains the JWE can recover the plaintext and forge or modify the content. This is fixed in version 0.6.2.6 by `_cjose_jwe_set_cek_aes_cbc()` generating the CEK from `RAND_bytes`. A regression test asserts that the `encrypted_key` differs across two encryptions for each AES-CBC-HMAC variant. Until upgrading, for data encrypted with cjose, three options are available. Use an AES-GCM `enc` (`A128GCM` / `A192GCM` / `A256GCM`) instead of an AES-CBC-HMAC `enc`, use `alg=dir` with a caller-supplied CEK, or avoid using cjose for JWE encryption with the affected algorithm pair. These are mitigations for new ciphertexts only; data already encrypted under the zero key remains compromised and should be re-encrypted (and any secrets it contained rotated).

Patch / fix

  • cisco cjose 0.6.2.6
  • cjose Debian 12 0.6.2.1-1+deb12u2
  • cjose Debian 13 0.6.2.3-1+deb13u1
  • cjose Debian 14 0.6.2.7-1

debian advisories DEBIAN-CVE-2026-53939

  • cjose RHEL 10.2 0.6.2.2-7.el10_2.2
  • cjose enterprise linux eus 10.0 0.6.2.2-7.el10_0.2

red hat advisories RHSA-2026:83224RHSA-2026:80605

  • cjose SLES for SAP applications 16.0, SLES 16.0 0.6.2.3-160000.3.1
  • cjose SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES 15 SP5-LTSS +5 more 0.6.1-150100.4.9.1
  • cjose SLES for SAP 15 SP6, SLES 15 SP6-LTSS, SLE Module for Server Applications 15 SP7 0.6.1-150600.18.3.1
  • cjose SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 0.6.1-7.8.1

suse advisories SUSE-SU-2026:23910-1SUSE-SU-2026:4253-1SUSE-SU-2026:4251-1SUSE-SU-2026:4237-1

  • cjose openSUSE Leap 16.0 0.6.2.3-160000.3.1
  • cjose openSUSE Tumbleweed 0.6.2.8-2.1

opensuse advisories openSUSE-SU-2026:21944-1openSUSE-SU-2026:11784-1

  • cjose AlmaLinux 8 0.6.1-6.module_el8.10.0+4330+15616d81
  • mod_auth_openidc AlmaLinux 8 2.4.9.4-9.module_el8.10.0+4297+63ae3533
  • cjose AlmaLinux 9 0.6.1-17.el9_8.2
  • cjose AlmaLinux 10 0.6.2.2-7.el10_2.2

almalinux advisories ALSA-2026:92157ALSA-2026:92145ALSA-2026:80605

  • cjose Rocky Linux 9 0.6.1-17.el9_8.2
  • mod_auth_openidc Rocky Linux 8 2.4.9.4-9.module+el8.10.0+40373+8a3f15d2
  • cjose Rocky Linux 10 0.6.2.2-7.el10_2.2

rocky linux advisories RLSA-2026:92145RLSA-2026:92157RLSA-2026:80605

Is CVE-2026-53939 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2026-53939 updated cvss 9.1

cjose: OpenIDC/cjose uses all-zero Content Encryption Key for AES-CBC-HMAC JWE encryption

  • Red Hat CodeReady Linux Builder EUS (v.9.6) cjose-devel 0.6.1-17.el9_6.2, cjose-debuginfo 0.6.1-17.el9_6.2, cjose-debugsource 0.6.1-17.el9_6.2
    fixed: vendor fix RHSA-2026:92154
  • Red Hat Enterprise Linux AppStream (v. 8) cjose 0.6.1-6.module+el8.10.0+25174+9c399f63, mod_auth_openidc 2.4.9.4-9.module+el8.10.0+24880+4db9166e
    fixed: vendor fix RHSA-2026:92157
  • Red Hat Enterprise Linux AppStream (v. 9) cjose 0.6.1-17.el9_8.2
    fixed: vendor fix RHSA-2026:92145
  • Red Hat Enterprise Linux AppStream (v. 10) cjose 0.6.2.2-7.el10_2.2, cjose 0.6.2.2-8.el10_3.1
    fixed: vendor fix RHSA-2026:80605
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) cjose 0.6.1-3.module+el8.4.0+25223+40c6a3da.2, mod_auth_openidc 2.4.9.4-1.module+el8.4.0+24868+593d10ef.3
    fixed: vendor fix RHSA-2026:92160
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) cjose 0.6.1-3.module+el8.6.0+25217+11ffe348.2, mod_auth_openidc 2.4.9.4-1.module+el8.6.0+24867+df0294a5.3
    fixed: vendor fix RHSA-2026:92159
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) cjose 0.6.1-3.module+el8.8.0+25209+e122577f.2, mod_auth_openidc 2.4.9.4-1.module+el8.8.0+24885+7d8e9f68.3
    fixed: vendor fix RHSA-2026:92158
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) cjose 0.6.1-13.el9_2.2
    fixed: vendor fix RHSA-2026:92156
show 9 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) cjose 0.6.1-16.el9_4.2
    fixed: vendor fix RHSA-2026:92155
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) cjose 0.6.2.2-7.el10_0.2
    fixed: vendor fix RHSA-2026:83224
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) cjose 0.6.1-17.el9_6.2
    fixed: vendor fix RHSA-2026:92154
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) cjose 0.6.1-3.module+el8.4.0+25223+40c6a3da.2, mod_auth_openidc 2.4.9.4-1.module+el8.4.0+24868+593d10ef.3
    fixed: vendor fix RHSA-2026:92160
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) cjose 0.6.1-3.module+el8.6.0+25217+11ffe348.2, mod_auth_openidc 2.4.9.4-1.module+el8.6.0+24867+df0294a5.3
    fixed: vendor fix RHSA-2026:92159
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) cjose 0.6.1-3.module+el8.8.0+25209+e122577f.2, mod_auth_openidc 2.4.9.4-1.module+el8.8.0+24885+7d8e9f68.3
    fixed: vendor fix RHSA-2026:92158
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 9) cjose-devel 0.6.1-17.el9_8.2, cjose-debuginfo 0.6.1-17.el9_8.2, cjose-debugsource 0.6.1-17.el9_8.2
    fixed: vendor fix RHSA-2026:92145
  • Red Hat Enterprise Linux CodeReady Linux Builder (v. 10) cjose-devel 0.6.2.2-7.el10_2.2, cjose-devel 0.6.2.2-8.el10_3.1, cjose-debuginfo 0.6.2.2-7.el10_2.2, cjose-debuginfo 0.6.2.2-8.el10_3.1, cjose-debugsource 0.6.2.2-7.el10_2.2, cjose-debugsource 0.6.2.2-8.el10_3.1
    fixed: vendor fix RHSA-2026:80605
  • Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0) cjose-devel 0.6.2.2-7.el10_0.2, cjose-debuginfo 0.6.2.2-7.el10_0.2, cjose-debugsource 0.6.2.2-7.el10_0.2
    fixed: vendor fix RHSA-2026:83224

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
yes
Technical impact
total
Assessed
2mo ago

Exploit prediction

0.25% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/OpenIDC/cjose/security/advisories/GHSA-f6wf-pqg3-6wqq referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 9.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

  • OpenIDC cjose

Classification

Weakness
  • CWE-321 Use of Hard-coded Cryptographic Key
  • CWE-330 Use of Insufficiently Random Values

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 OpenIDC/cjose 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.