CVE-2026-74900Network attack vector

Plaintext recovery via deterministic KEM fallback

Published Aug 17, 2026 · Updated Aug 17, 2026

Weak shared-secret generation in jahlives OpenSSL Encrypt before 1.4.0 allows attackers to decrypt ciphertext via KEM failure fallback. In openssl_encrypt/modules/pqc.py, decrypt() silently substitutes a simulation secret computed from encapsulated_key and public_key_part(private_key), while public_key_part() returns only the first 16 private-key bytes. Any KEM decapsulation error reaches this path without a hard failure, so attackers who know those 16 bytes and the public encapsulated key can recover plaintext from affected ciphertexts.

CVSS severity9.3
Critical
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Weak shared-secret generation in jahlives OpenSSL Encrypt before 1.4.0 allows attackers to decrypt ciphertext via KEM failure fallback. In openssl_encrypt/modules/pqc.py, decrypt() silently substitutes a simulation secret computed from encapsulated_key and public_key_part(private_key), while public_key_part() returns only the first 16 private-key bytes. Any KEM decapsulation error reaches this path without a hard failure, so attackers who know those 16 bytes and the public encapsulated key can recover plaintext from affected ciphertexts.

The record

CVE
CVE-2026-74900
Published
Aug 17, 2026
Updated
Aug 17, 2026
Vendor
jahlives
Product
OpenSSL Encrypt
Classifications
CWE-391
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 17, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

jahlives · OpenSSL Encryptversion=0 <1.4.0

Published CVSS scores

9.8VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-391Unchecked Error Condition

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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