CVE-2026-35188

Issue summary: A malicious server can exploit TLS OCSP stapling by delivering a crafted response through the status_request extension, triggering a double-free in the client's certificate verification path.

Impact summary: Successful exploitation allows an attacker to corrupt heap memory via a double-free, potentially leading to a Denial of Service or possibly an attacker controlled code execution or other undefined behavior.

If OCSP stapling is enabled and the TLS client connects to a malicious server, a crafted OCSP stapled response can trigger a double free in the TLS client when the stapled response is checked.

The OCSP stapling is not enabled by default. Reliable code execution through a double-free is technically complex and highly environment-dependent but the Denial of Service impact is straightforward to achieve, warranting Moderate severity.

No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.

Database specific

{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/35xxx/CVE-2026-35188.json",
    "cna_assigner": "openssl",
    "cwe_ids": [
        "CWE-415"
    ]
}

References

Affected packages

Git / github.com/openssl/openssl

Affected ranges

Type

GIT

Repo

https://github.com/openssl/openssl

Events

Introduced

7b371d80d959ec9ab4139d09d78e83c090de9779

Fixed

aae016bfd52fcad2bc9657c2c782cfdf73b1ed5f

Introduced

11b7b6ea3b65a584e1d31408ed1bdb139465cffd

Fixed

131145d25659e8749a9ed1afb383484854cffb78

Fixed

78d0154cffda03aaaac63a087cc523a6b35fa8fd

Database specific

{
    "source": [
        "CPE_RANGE",
        "CPE_STRING",
        "REFERENCES"
    ],
    "cpe": [
        "cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*",
        "cpe:2.3:a:openssl:openssl:4.0.0:-:*:*:*:*:*:*"
    ],
    "extracted_events": [
        {
            "introduced": "3.6.0"
        },
        {
            "fixed": "3.6.3"
        },
        {
            "introduced": "4.0.0-NA"
        },
        {
            "last_affected": "4.0.0-NA"
        }
    ]
}

Affected versions

3.*

3.6-POST-CLANG-FORMAT-WEBKIT

3.6-PRE-CLANG-FORMAT-WEBKIT

4.*

4.0.0-NA

openssl-3.*

openssl-3.6.0

openssl-3.6.1

openssl-3.6.2

openssl-4.*

openssl-4.0.0

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-35188.json"