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Vulnerabilities

Vulnerability · 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…

Published Jun 9, 2026 · catalog updated Jul 23, 2026 · the affected product

Last checked Nov 10, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2026-35188. EPSS is 0.30%. Act only if a listed version of the affected product is installed.

Gaps on this record

  • No plain product name is stored. The page cannot tell you which product to check.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium5.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.30%
Remediation
Version ranges on file
Affected products
cpe openssl/openssl

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe openssl/openssl4.0.0
  • cpe openssl/openssl< 3.6.3

How to fix CVE-2026-35188

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-35188. EPSS is 0.30%. Act only if a listed version of the affected product is installed.

Which versions are affected?

Compare what you have installed with 4.0.0, < 3.6.3. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-415: Double Free. EPSS 0.30%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

OpenSSL security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Jun 9, 2026 · Monitored products — critical

    Detected

    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

  2. Jul 23, 2026 · Monitored products — critical

    Updated

    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

Sources

  • CVE.orgVulnerability recordCVE-2026-35188

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-35188

    30-day exploitation probability 0.30%

    first.org
  • Monitored products — criticalVendor advisoryCVE-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

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 10, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSNov 7, 2026
  • CVE.orgNov 4, 2026
  • Monitored products — criticalNov 4, 2026