Skip to content
Noroxi
NVD / CVE Program· CNA openssl

CVE-2026-35188: Double-free When Checking OCSP Stapled Response

Noroxi assessment

Priority: Monitor (action score 20/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.30% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: OpenSSL OpenSSL 3.6.3, 4.0.1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to OpenSSL OpenSSL 3.6.3, 4.0.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.0 · v3.1—No exploit Fix available
Published
Jun 9, 2026
Updated
Jul 23, 2026
EPSS
0.3% · 23th percentile

Report tools

JSON

Action score

20

Monitor

Low priority for now.

CVSS
20 / 40 · 5.0 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-35188

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits instantly.

Your free account also gets you

Running WordPress? Scan your site free with WP Lens

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for openssl records

Running WordPress? Scan your site free with WP Lens

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
opensslopenssl

Check your server's TLS configuration

The OpenSSL version can't be seen from outside; the free SSL checker tests your certificate, enabled TLS versions and weak ciphers. Confirm the version on your server with the package manager.

Run the SSL check

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • openssl openssl3.6.0 and later · before 3.6.3
  • openssl openssl4.0.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (openssl). Independent of NVD's CPE analysis and usually ahead of it.

  • OpenSSL OpenSSL

    • 4.0.0 and later · before 4.0.1affected · semver
    • 3.6.0 and later · before 3.6.3affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:14opensslbefore 3.6.3-13.6.3-1
Red Hat:hummingbird:1bootupdbefore 0:0.3.2-1.hum10:0.3.2-1.hum1
Red Hat:hummingbird:1chunkahbefore 0:0.6.0-3.hum10:0.6.0-3.hum1
Red Hat:hummingbird:1opensslbefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl-config-fipsbefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl-develbefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl-devel-enginebefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl-fips-provider-upstreambefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl-libsbefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl-perlbefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl3before 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl3-develbefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl3-devel-enginebefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1openssl3-libsbefore 0:3.5.8-0.1.hum10:3.5.8-0.1.hum1
Red Hat:hummingbird:1python-cryptographybefore 0:50.0.0-1.hum10:50.0.0-1.hum1
Red Hat:hummingbird:1python3-cryptographybefore 0:50.0.0-1.hum10:50.0.0-1.hum1
Red Hat:hummingbird:1ruby3.3before 0:3.3.10-23.6.hum10:3.3.10-23.6.hum1
Red Hat:hummingbird:1ruby3.3-bundled-gemsbefore 0:3.3.10-23.6.hum10:3.3.10-23.6.hum1
Red Hat:hummingbird:1ruby3.3-default-gemsbefore 0:3.3.10-23.6.hum10:3.3.10-23.6.hum1
Red Hat:hummingbird:1ruby3.3-develbefore 0:3.3.10-23.6.hum10:3.3.10-23.6.hum1
Red Hat:hummingbird:1ruby3.3-docbefore 0:3.3.10-23.6.hum10:3.3.10-23.6.hum1
Red Hat:hummingbird:1ruby3.3-libsbefore 0:3.3.10-23.6.hum10:3.3.10-23.6.hum1
Red Hat:hummingbird:1ruby3.4before 0:3.4.10-31.7.hum10:3.4.10-31.7.hum1
Red Hat:hummingbird:1ruby3.4-bundled-gemsbefore 0:3.4.10-31.7.hum10:3.4.10-31.7.hum1

+47

Same product

openssl: all records

Other highest-scoring records for the same primary product.

  • CVE-2014-0160The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly handle Heartbeat Extension packets, which allows remKEV
    90Now
  • CVE-2021-3711SM2 Decryption Buffer Overflow
    65This week
  • CVE-2003-0545Double free vulnerability in OpenSSL 0.9.7 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code
    65This week

Published before and after this one in the same product

  • ← EarlierCVE-2026-34182Jun 9, 2026 · CMS AuthEnvelopedData Processing May Accept Forged Messages
    36Monitor
  • ← EarlierCVE-2026-34183Jun 9, 2026 · Unbounded Memory Growth in the QUIC PATH_CHALLENGE Handler
    30Monitor
  • Later →CVE-2026-42764Jun 9, 2026 · NULL Pointer Dereference in QUIC Server Initial Packet Handling
    30Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
OpenSSL OpenSSL3.6.3Vendor (CNA)
OpenSSL OpenSSL4.0.1Vendor (CNA)
azl3 cloud-hypervisor 52.0.152-1 on Azure Linux 3.0—Microsoft (MSRC)
debian:openssl3.6.3-1 · Debian:14Package registry (OSV)
red hat:chunkah0:0.6.0-3.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-config-fips0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-devel0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-devel-engine0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl-fips-provider-upstream0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl30:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl3-devel0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl3-devel-engine0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:openssl3-libs0:3.5.8-0.1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python-cryptography0:50.0.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:python3-cryptography0:50.0.0-1.hum1 · Red Hat:hummingbird:1Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-1879877 days apartQUIC Server May Trigger Double Free When Processing INITIAL Packet
    31Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
low · data can be read
Integrity
low · data or configuration can be modified
Availability
low · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
Low
Availability impact
Low

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records