CVE-2026-74900: openssl_encrypt versions before 1.4.0 contain a critical vulnerability in pqc.py where KEM decapsulation failu

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CRITICAL 9.8REMOTEWATCHLISTUPGRADE

CVE-2026-74900 is a critical-severity flaw (CVSS 9.8) affecting openssl encrypt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 er

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 54%)
CISA exploited list	No
Weakness	CWE-391
Published	2026-08-17
Last modified	2026-09-01

Publisher (CNA): VulnCheck · Vendor: jahlives

Last updated 2026-09-01 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-17 11:16 UTCPublished CVE record published
2026-09-01 15:24 UTCUpdated Record last modified

jahlives openssl encrypt UPGRADE

Affected: < 1.4.0

Fixed in: 1.4.0

Safe to downgrade to: no unaffected older release

1. Check installed version

pip show openssl-encrypt

2. UPGRADE to 1.4.0

pip install --upgrade "openssl-encrypt>=1.4.0"

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-74900?

openssl encrypt: upgrade to 1.4.0. Exact commands for each OS are on this page.

Is CVE-2026-74900 being exploited?

CVE-2026-74900 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-74900 affect?

CVE-2026-74900 affects openssl encrypt. Severity is critical (CVSS 9.8). 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 publ

How urgent is CVE-2026-74900?

Priority 56/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities

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CVE-2026-74890 MEDIUM 5.5 UPGRADE openssl_encrypt versions before 1.4.0 contain an authentication bypass vulnerability in CamelliaCipher that di
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References

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