CVE-2026-74900 json
openssl_encrypt before 1.4.0 Weak Shared Secret via PQC Simulation Mode
published 2026-08-17 2 mo ago modified 2026-10-01 39 d ago also GHSA-p3gq-pcg9-qvfv , PYSEC-2026-3772 , EUVD-2026-60117
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 46%
- public exploits
- 0
- none known
Summary
openssl_encrypt versions before 1.4.0 contain a critical vulnerability in pqc.py where KEM decapsulation failures silently fall back to simulation mode, generating a deterministic shared secret from only 16 bytes of the private key and publicly available encapsulated key data. Attackers who obtain 16 bytes of the private key can compute the shared secret and decrypt all ciphertext, as the fallback triggers on any KEM failure without raising an error.
Patch / fix
- pypi openssl-encrypt 1.4.0
- jahlives openssl_encrypt 1.4.0
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 2 mo ago
Exploit prediction
0.56% chance of exploitation in the next 30 days, higher than 46% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 4.0 | 9.3 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/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 |
|---|---|---|---|
| pypi | openssl-encrypt | <1.4.0 |
1.4.0 |
Affected products
- jahlives openssl_encrypt
Classification
- Weakness
-
- CWE-391 DEPRECATED: Unchecked Error Condition
References
-
github.com
/jahlives/openssl_encrypt/security/advisories/GHSA-p3gq-pcg9-qvfv
vendor-advisory, mitigation, advisory
-
vulncheck.com
/advisories/openssl-encrypt-before-weak-shared-secret-via-pqc-simulation-mode
third-party-advisory, advisory
Sources
- CVE List CVE-2026-74900
- NVD CVE-2026-74900
- OSV PYSEC-2026-3772
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.