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CVE-2026-63076— Invalid Pointer Dereference in CMP Server via Crafted protectionAlg

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之前版本存在异常处理不当漏洞，该漏洞源于CMP密码保护验证中未检查protectionAlg参数类型，仅检查指针非空，导致空指针取消引用，远程未经身份验证的攻击者可利用该漏洞导致拒绝服务。

AI Predicted 5.3 Difficulty: Easy EPSS 1.60% · P76

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

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-2026-63076

Vulnerability Information
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Vulnerability Title
Invalid Pointer Dereference in CMP Server via Crafted protectionAlg
Source: CVE Program / CVE List V5
Vulnerability Description
Issue summary: OpenSSL CMP password based protection verification only checks whether the protectionAlg parameter was not NULL and not its ASN.1 type, before treating it as a PBMParameter. A crafted message can contain a parameter of a different type, which is then dereferenced as an invalid pointer. Impact summary: A remote, unauthenticated attacker can crash an application acting as a CMP server that accepts PBM-protected messages, or a CMP client talking to a malicious or intercepted CMP server, resulting in a Denial of Service. CWE: CWE-476: NULL Pointer Dereference Description: When verifying the password-based MAC protection of a CMP message, OpenSSL library reads the protectionAlg algorithm parameter with X509_ALGOR_get0(), which returns both the parameter type and its value pointer. The value is then cast to an ASN1_STRING and treated as the expected PBMParameter after only checking that pointer is not NULL. The parameter type returned by X509_ALGOR_get0() was never consulted. This happens during protection verification, before any MAC is computed, so no knowledge of the PBM shared secret is required; the only precondition is that PBM verification is reachable. On the server side this is reached from OSSL_CMP_SRV_process_request() for any application that stands up a CMP server accepting PBM-protected messages, and on the client side from CMP response validation against a malicious or on-path (MITM) server. The reliable consequence is a denial of service; there is no memory disclosure, no controlled memory write, and no path to code execution. CMP is a specialized feature that an application must explicitly enable. FIPS impact: no As the CMP code lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
空指针解引用
Source: CVE Program / CVE List V5
Vulnerability Title
OpenSSL 异常处理不当漏洞
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之前版本存在异常处理不当漏洞，该漏洞源于CMP密码保护验证中未检查protectionAlg参数类型，仅检查指针非空，导致空指针取消引用，远程未经身份验证的攻击者可利用该漏洞导致拒绝服务。
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-2026-63076

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III. Intelligence Information for CVE-2026-63076

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Patches & Fixes for CVE-2026-63076 (5)

Vendor Advisories for CVE-2026-63076 (1)

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

CVE-2026-75803 AEAD Forgeries with Empty Ciphertext When Using EVP_Cipher()
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-2026-14457 RPK Server Signature Algorithm Selection Can Dereference a Missing Certificate

IV. Related Vulnerabilities

Same product: OpenSSL
Same vendor: OpenSSL
Same weakness: CWE-476

V. Comments for CVE-2026-63076

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