CVE-2026-75803: Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty ciphertext can report success without ve

Q: How do I fix CVE-2026-75803?

openssl: upgrade to 3.0.22, 3.4.7, 3.5.8, 3.6.4, 4.0.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-75803 being exploited?

CVE-2026-75803 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-75803 affect?

CVE-2026-75803 affects openssl. Severity is critical (CVSS 9.1). Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty ciphertext can report success without verifying the supplied authentication tag when the operation is finalized by calling the EVP_Cipher() function. Impact summary: App

Q: How urgent is CVE-2026-75803?

Priority 46/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

This month

CRITICAL 9.1REMOTEWATCHLISTUPGRADE

CVE-2026-75803 is a critical-severity flaw (CVSS 9.1) affecting openssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty ciphertext can report success without verifying the supplied authentication tag when the operation is finalized by calling the EVP_Cipher() function. Impact summary: Applications calling EVP_Cipher() on an empty ciphertext and expecting the call to check the AEAD tag may accept forged messages. CWE: CWE-354 (Improper Validation of Integrity Check Value) Description: The EVP_

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	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 83%)
CISA exploited list	No
Weakness	CWE-354
Published	2026-08-25
Last modified	2026-09-11

Publisher (CNA): OpenSSL Software Foundation · Vendor: openssl

Last updated 2026-09-11 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-25 13:19 UTCPublished CVE record published
2026-09-11 21:17 UTCUpdated Record last modified

openssl openssl UPGRADE

Affected: >= 3.0.0 and < 3.0.22 · >= 3.4.0 and < 3.4.7 · >= 3.5.0 and < 3.5.8 · >= 3.6.0 and < 3.6.4 · >= 4.0.0 and < 4.0.2

Fixed in: 3.0.22, 3.4.7, 3.5.8, 3.6.4, 4.0.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy openssl || rpm -q openssl || openssl --version

2. UPGRADE to 3.0.22 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade openssl

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade openssl

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2026-75803?

openssl: upgrade to 3.0.22, 3.4.7, 3.5.8, 3.6.4, 4.0.2. Exact commands for each OS are on this page.

Is CVE-2026-75803 being exploited?

CVE-2026-75803 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-2026-75803 affect?

CVE-2026-75803 affects openssl. Severity is critical (CVSS 9.1). Issue summary: ChaCha20-Poly1305 and AES-OCB decryption with an empty ciphertext can report success without verifying the supplied authentication tag when the operation is finalized by calling the EVP_Cipher() function. Impact summary: App

How urgent is CVE-2026-75803?

Priority 46/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

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References

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