CVE-2026-75803

AEAD forgery via skipped empty-ciphertext tag verification

Published Aug 25, 2026 · Updated Aug 25, 2026

Integrity-check bypass in OpenSSL allows attackers to submit forged empty ChaCha20-Poly1305 or AES-OCB messages through EVP_Cipher(). The built-in cipher callbacks treat a NULL-input terminal call as success without comparing the supplied AEAD tag when ciphertext is empty. Exposure requires a consuming application to decrypt an empty ciphertext with EVP_Cipher() and trust its success result; the bounded consequence is acceptance of forged message content.

CVSS severity5.3
Medium
EPSS probability0.22%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integrity-check bypass in OpenSSL allows attackers to submit forged empty ChaCha20-Poly1305 or AES-OCB messages through EVP_Cipher(). The built-in cipher callbacks treat a NULL-input terminal call as success without comparing the supplied AEAD tag when ciphertext is empty. Exposure requires a consuming application to decrypt an empty ciphertext with EVP_Cipher() and trust its success result; the bounded consequence is acceptance of forged message content.

The record

CVE
CVE-2026-75803
Published
Aug 25, 2026
Updated
Aug 25, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-354, T1565.002
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Aug 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3Amazon LinuxCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A: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)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-354Improper Validation of Integrity Check Value
T1565.002Transmitted Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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