CVE-2026-53939
Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:NCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-53939 is a critical-severity Use of Hard-coded Cryptographic Key (CWE-321) vulnerability. Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Brute Force (T1110); ranked at the 10th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-12 (Cryptographic Key Establishment and Management) and SC-13 (Cryptographic Protection) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-74299
Vulnerability Data
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…
more
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).
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
—
—
- 8 hardening rules · 4 OS baselines
—
Mitigating Controls (NIST 800-53 r5) AI
Requiring cryptographic keys to be established and managed according to defined requirements prevents developers from embedding static unchangeable keys.
SC-13 requires selection and implementation of approved cryptographic algorithms and methods, which inherently depend on and enforce sufficiently random values.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Data-at-rest protection policies require proper key management and therefore discourage hard-coded keys.
Data-in-transit protection similarly depends on non-hard-coded keys for encryption.
Configuration baselines and reviews can prohibit hard-coded keys in deployed artifacts.
Secure-SDLC activities such as code review and secret scanning directly prevent embedding static keys.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Key-management controls that govern generation, rotation and protection of keys make the use of embedded hard-coded cryptographic keys less likely and easier to detect.
Secure SDLC processes include verification steps that can catch insufficient randomness but do not directly specify RNG requirements.
Secure coding standards explicitly prohibit use of weak or predictable random number generators.
Security testing can detect weak randomness but does not prescribe the control itself.
Secure authentication mechanisms depend on unpredictable values (nonces, salts, session tokens) to resist guessing.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).
Oracle Linux 8 (3 rules)
- V-248563 The OL 8 SSH server must be configured to use strong entropy. prevents CWE-330
- V-248599 OL 8 must enable the hardware random number generator entropy gatherer service. prevents CWE-330
- V-248600 OL 8 must have the packages required to use the hardware random number generator entropy gatherer service. prevents CWE-330
Oracle Linux 9 (1 rule)
- V-271511 OL 9 must enable the hardware random number generator entropy gatherer service. prevents CWE-330
RHEL 8 (3 rules)
- V-244527 RHEL 8 must have the packages required to use the hardware random number generator entropy gatherer service. prevents CWE-330
- V-230253 RHEL 8 must ensure the SSH server uses strong entropy. prevents CWE-330
- V-230285 RHEL 8 must enable the hardware random number generator entropy gatherer service. prevents CWE-330
RHEL 9 (1 rule)
- V-257782 RHEL 9 must enable the hardware random number generator entropy gatherer service. prevents CWE-330