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CVE-2026-75803— AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()

Quick assessment

Affected
OpenSSL OpenSSL
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

OpenSSL是OpenSSL团队开源的一个提供安全通信加密功能的软件库。 OpenSSL 4.0.0版本至4.0.2之前版本、3.6.0版本至3.6.4之前版本、3.5.0版本至3.5.8之前版本、3.4.0版本至3.4.7之前版本和3.0.0版本至3.0.22之前版本存在加密问题漏洞，该漏洞源于对完整性检查值验证不当，当通过EVP_Cipher()函数处理空密文时可能跳过AEAD标签验证，导致应用程序接受伪造消息。

AI Predicted 7.5 Difficulty: Hard EPSS 0.23% · P13

Possible ATT&CK Techniques 1 AI

T1059.007 · JavaScript

Affected Version Matrix 5

VendorProduct Version RangeStatus
OpenSSL OpenSSL 4.0.0< 4.0.2 affected
3.6.0< 3.6.4 affected
3.5.0< 3.5.8 affected
3.4.0< 3.4.7 affected
3.0.0< 3.0.22 affected
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I. Basic Information for CVE-2026-75803

Vulnerability Information
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Vulnerability Title
AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()
Source: CVE Program / CVE List V5
Vulnerability Description
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_Cipher() API call for AEAD ciphers behaves like a one shot encryption and decryption call. It also verifies the AEAD tag after the decryption operation. However for AES-OCB and ChaCha20-Poly1305 ciphers it skipped the AEAD tag verification when an empty ciphertext was passed to the function. The callers of this function might believe that a successful return indicates a valid AEAD tag for these ciphers, even when that has not truly been validated in this case. FIPS impact: no The FIPS modules in 4.0, 3.6, 3.5, 3.4, and 3.0 are not affected by this CVE as the affected algorithms are not FIPS approved and thus not implemented in the FIPS module.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
完整性检查值验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
OpenSSL 加密问题漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
OpenSSL是OpenSSL团队开源的一个提供安全通信加密功能的软件库。 OpenSSL 4.0.0版本至4.0.2之前版本、3.6.0版本至3.6.4之前版本、3.5.0版本至3.5.8之前版本、3.4.0版本至3.4.7之前版本和3.0.0版本至3.0.22之前版本存在加密问题漏洞，该漏洞源于对完整性检查值验证不当，当通过EVP_Cipher()函数处理空密文时可能跳过AEAD标签验证，导致应用程序接受伪造消息。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
OpenSSL OpenSSL 4.0.0 ~ 4.0.2 -

II. Public POCs for CVE-2026-75803

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III. Intelligence Information for CVE-2026-75803

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Patches & Fixes for CVE-2026-75803 (5)

Vendor Advisories for CVE-2026-75803 (1)

Same Patch Batch · OpenSSL · 2026-08-25 · 9 CVEs total

CVE-2026-18798 QUIC Server May Trigger Double Free When Processing INITIAL Packet
CVE-2026-54874 Excessive Memory Use Buffering DTLS Records for a Future Epoch
CVE-2026-63074 CMP Indefinite Cache Growth of ExtraCerts
CVE-2026-63072 Heap Buffer Overflow in CMS Key Unwrapping
CVE-2026-63073 Untrusted Sender DN Used as Format String in CMP Response Validation
CVE-2026-63075 QUIC ACK-only Packet Retention Can Cause Memory Exhaustion
CVE-2026-63076 Invalid Pointer Dereference in CMP Server via Crafted protectionAlg
CVE-2026-14457 RPK Server Signature Algorithm Selection Can Dereference a Missing Certificate

IV. Related Vulnerabilities

Same product: OpenSSL
Same vendor: OpenSSL
Same weakness: CWE-354

V. Comments for CVE-2026-75803

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