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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.

问题摘要： OpenSSL 中基于 CMP（证书管理协议）的基于密码的保护验证机制存在缺陷。该验证逻辑仅检查 参数是否非 NULL，而未验证其 ASN.1 类型，随后便将其当作 处理。攻击者可构造特殊消息，其中包含类型不同的参数，导致程序将其解引用为无效指针，从而引发问题。 影响摘要： 远程、未认证的攻击者可使作为 CMP 服务器且接受基于密码保护（PBM）消息的应用程序崩溃，或使与恶意或中间人（MITM）攻击的 CMP 服务器进行通信的 CMP 客户端崩溃，从而导致拒绝服务（DoS）。 CWE： CWE-476：

AI Predicted 5.3 Difficulty: Easy

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

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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