OpenSSL: NULL Pointer Dereference
CVE-2026-63076 is a high-severity NULL pointer dereference vulnerability in OpenSSL, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 4.0.2, 3.6.4, 3.5.8 as the first without the flaw, so updating OpenSSL to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.6% chance of exploitation within 30 days, higher than 76% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update OpenSSL to 4.0.2 or 3.6.4 or 3.5.8 or 3.4.7, whichever matches your release line, or a later version.
- Read the advisory on openssl-library.org for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| OpenSSL | OpenSSL | 4.0.0 up to, but not including, 4.0.2; 3.6.0 up to, but not including, 3.6.4; 3.5.0 up to, but not including, 3.5.8; 3.4.0 up to, but not including, 3.4.7; 3.0.0 up to, but not including, 3.0.22 | 4.0.2, 3.6.4, 3.5.8, 3.4.7, 3.0.22 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- NoneNo data is disclosed.
- Integrity
- NoneNothing can be modified.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CISA (ADP).
Official 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: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: NULL Pointer Dereference
The product dereferences a pointer that it expects to be valid but is NULL.
How developers prevent this class of flaw
- For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
- Select a programming language that is not susceptible to these issues.
- Check the results of all functions that return a value and verify that the value is non-null before acting upon it.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- github.com/openssl/openssl/commit/37882aa2e0256e1072442a8f62f7db45b995c45b
- github.com/openssl/openssl/commit/a17cc8d612ecff6d94a9b7ca8b5283ddf5ff570e
- github.com/openssl/openssl/commit/a1f348ccb328c3afbd4ba6883f9b7c813c043259
- github.com/openssl/openssl/commit/a7af46a92d0ce19a90e669ef56d2576a07924226
- github.com/openssl/openssl/commit/cdacfff557389abfa9e4615abded2ec984517d6c
Other vulnerabilities in OpenSSL
- 7.5 High severity
- 7.5 High severity
- 8.2 High severity
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
Recent NULL Pointer Dereference vulnerabilities
- 8.2 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.1 High severity
- 7.5 High severity
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