openssl_encrypt versions before 1.4.0 contain a critical vulnerability in pqc.py where KEM decapsulation failures silent
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.
Affected packages
- openssl-encrypt— before 1.4.0
Exploit signal
- Known exploited (CISA KEV)
- No
- EPSS score
- —
- EPSS percentile
- —
EPSS is the probability a CVE is exploited in the wild; percentile is its rank among all CVEs.
Sources
- https://github.com/jahlives/openssl_encrypt/security/advisories/GHSA-p3gq-pcg9-qvfv
- https://www.vulncheck.com/advisories/openssl-encrypt-before-weak-shared-secret-via-pqc-simulation-mode
Structured record: https://osv.dev/vulnerability/PYSEC-2026-3772
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