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OpenSSL CVE-2026-35189

| EUVDEUVD-2026-89001 MEDIUM
Allocation of Resources Without Limits or Throttling (CWE-770)
2026-09-29 GHSA-3r46-fh9h-qv77
Denial Of Service OpenSSL
5.3
CVSS 3.1 · Vendor
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Deliver crafted certificate with relative CRLDP
  2. Exploit
    Trigger relative CRLDP processing in OpenSSL
  3. Execution
    Excessive memory allocation (CWE-770)
  4. Impact
    Resource exhaustion / partial denial of service

Vulnerability Assessment

Weakness
CWE
CWE-770
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V2 - Validation and Business Logic Resource allocation limits
MITRE ATT&CK

1 technique across 1 tactic: Impact

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

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Exploitation Conditions

Exploitation requires that the target application use OpenSSL to perform X.509 certificate/CRL validation involving relative CRL Distribution Point (relative-name CRLDP) processing, and that an attacker can supply a crafted certificate to that code path (e.g., via a TLS handshake presenting a malicious client/server certificate, or any service that ingests and validates attacker-controlled certificates). The limiting factor is that an application must actually reach the relative-CRLDP processing logic - applications that do not perform CRL distribution point handling on untrusted certificates are not exposed. No authentication is required (PR:N) and no user interaction (UI:N); impact is limited to availability degradation (A:L), not code execution or data exposure.
Impact

This is a genuine but low-severity denial-of-service issue, not a high-priority emergency. All signals are consistent and point the same direction: the CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L, base 5.3) scores only partial availability impact with no confidentiality or integrity loss, and CWE-770 (uncontrolled resource allocation) matches the description of excessive memory allocation during relative CRL Distribution Point (CRLDP) processing. The CISA SSVC framework corroborates low urgency: Exploitation=none (no observed or public exploitation), Automatable=yes (the condition can be triggered reliably at scale once a crafted certificate is delivered), Technical Impact=partial (degraded, not total, service loss). There is no EPSS score, no CISA KEV listing, and no public proof-of-concept in the provided data - exploitation status is 'no public exploit identified at time of analysis.' The one minor tension is that Automatable=yes slightly elevates concern versus the otherwise-low profile, but it is bounded by the merely-partial impact (memory pressure/DoS rather than crash-with-code-execution). Net: real and worth patching as part of normal OpenSSL maintenance, but not a drop-everything priority. The dominant risk driver is prevalence - OpenSSL is ubiquitous, so a large install base is nominally affected even though per-instance impact is modest.
Exploit ScenarioDerived

An attacker causes a vulnerable application to parse an X.509 certificate (or certificate chain) containing a crafted relative CRL Distribution Point, for example by presenting such a certificate during a TLS handshake or submitting it to a service that performs certificate/CRL validation. During relative CRLDP processing OpenSSL allocates an excessive amount of memory, exhausting resources and degrading or denying service. No proof-of-concept is referenced in the provided data; exploitation is remote and unauthenticated (PR:N) with low attack complexity.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 01, 2026

Excessive memory allocation in OpenSSL's X.509 relative CRL Distribution Point (CRLDP) processing lets remote, unauthenticated attackers drive a low-impact denial of service against applications that validate attacker-supplied certificates or revocation data. Affected releases span OpenSSL 1.0.2 before 1.0.2zs, 1.1.1 before 1.1.1zj, 3.0.0 before 3.0.23, 3.4.0 before 3.4.8, 3.5.0 before 3.5.9, 3.6.0 before 3.6.5 and 4.0.0 before 4.0.3, and the flaw is fixed in the OpenSSL 4.0.3 security release (CWE-770, CVSS 5.3, availability-only). No public exploit code has been identified at time of analysis and no public exploit exists, exploitation is not confirmed (CISA SSVC records Exploitation: none, Automatable: yes, Technical Impact: partial), and real exposure requires the application to actually reach relative-CRLDP handling on untrusted input.

RemediationAI

Apply the vendor-released patch by upgrading to a fixed OpenSSL build: 4.0.3 for the 4.0.x line, 3.6.5, 3.5.9, 3.4.8, 3.0.23, 1.1.1zj or 1.0.2zs depending on the branch in use, since the fixes are shipped in the OpenSSL 4.0.3 security release (github.com/openssl/openssl/releases/tag/openssl-4.0.3) and detailed in the advisory at openssl-library.org/news/secadv/20260929.txt, with upstream commits including github.com/openssl/openssl/commit/2b93c73b2c70ddc4c61c5e4bfaaa6bd71379eb84; Ubuntu users should apply USN-8847-1. If upgrading cannot be done immediately, reduce exposure by preventing untrusted certificates from reaching CRL distribution point processing: avoid enabling CRL checking (for example X509_V_FLAG_CRL_CHECK / CRL_CHECK_ALL) on peer certificates that are not fully trusted, since CRLDP handling is what triggers the allocation, and apply process-level memory caps (cgroup limits or RLIMIT_AS) to TLS services that must validate attacker-supplied chains so that a single connection cannot exhaust host memory. Each workaround has a trade-off: disabling CRL checking weakens revocation enforcement, while hard memory limits may terminate the process under legitimate peak load rather than stopping the malicious allocation itself, so patching remains the only complete fix.

Affected VersionsENISA

OpenSSL 1.1.1 <1.1.1zj
OpenSSL 3.5.0 <3.5.9
OpenSSL 4.0.0 <4.0.3
OpenSSL 3.6.0 <3.6.5
OpenSSL 3.4.0 <3.4.8
OpenSSL 3.0.0 <3.0.23
OpenSSL 1.0.2 <1.0.2zs

Affected Packages

euvd openssl fix: 1.0.2zs, 1.1.1zj, 3.0.23, 3.4.8, 3.5.9, 3.6.5, 4.0.3

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

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Technical ContextAI · show details

OpenSSL's X.509 certificate verification code parses CRL Distribution Point (CRLDP) extensions, which tell a relying party where to fetch a Certificate Revocation List; a 'relative' distribution point uses a relative distinguished name rather than a full URI, and the code path that processes these relative-name CRLDPs failed to bound the memory it allocated. That is the root-cause class CWE-770 (Allocation of Resources Without Limits or Throttling): an attacker who can present a crafted certificate (for example during a TLS handshake as a client or server certificate, or to any service that ingests and validates attacker-controlled certificates) can cause uncontrolled allocation and degrade or exhaust memory in the validating process. The CVSS:3.1 vector AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L supplied with the entry confirms unauthenticated network reachability and an availability-only impact, matching the Denial Of Service tag and the SSVC 'partial' technical impact rating. The fix landed in the OpenSSL 4.0.3 security release and the corresponding maintenance branches, with the vendor advisory at openssl-library.org/news/secadv/20260929.txt and the patches visible in the referenced upstream commits (2b93c73b2c70ddc4c61c5e4bfaaa6bd71379eb84, 3842516cc15e8b2cf55747011045e77547e71d89, 8e0efc7549b7ff8246d40e585e3fd604f728473f, c72ae182cac17a82e4246c6ecd4e9c4ec3586ec9). Note that CVE-2026-35189 is one of several issues bundled in the same release alongside DTLS, QUIC, X.509 cache and constant-time fixes, so remediation must be verified against the specific branch in use.

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Severity by source

Vendor (CNA) PRIMARY 5.3 MEDIUM
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
vuln.today AI 5.3 MEDIUM

Remote unauthenticated delivery of a crafted certificate (AV:N/AC:L/PR:N/UI:N) triggering excessive memory allocation yields partial availability impact only (A:L), no confidentiality or integrity loss.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
SUSE MEDIUM
Red Hat 3.7 LOW

Primary rating from Vendor (CNA).

CVSS VectorVendor

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

Lifecycle Timeline

3
CVSS changed
Sep 30, 2026 - 22:08 NVD
5.3 (MEDIUM)
CVE Published
Sep 29, 2026 - 13:53 github-releases
MEDIUM 5.3
CVE Published
Sep 29, 2026 - 13:53 github-releases
UNKNOWN (no severity yet)

Description PRE-NVD

Disclosed via GitHub release of openssl/openssl. NVD scoring and full description are pending.

Threat Intelligence Overview

EPSS Score
0.3%
Top 83% exploitable
Prevalence
Ubiquitous
OpenSSL is a core TLS/crypto library in a vast fraction of environments
Data Quality
8 sources
Confidence: High
EUVD 🇯🇵JVN NVD CVE.org EPSS Vulnrichment MSRC Vendor GitHub VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

26
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +26
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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Same weakness CWE-770 – Allocation of Resources Without Limits or Throttling

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9.8
CVE-2011-0609 HIGH POC
7.8

Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
Container bci/bci-sle15-kernel-module-devel:15.7-61.25 Container bci/openjdk-devel:17.0.20.1-21.71 Container bci/openjdk-devel:21.0.12.1-25.71 Container bci/openjdk-devel:25.0.4.1-9.72 Container bci/openjdk:17.0.20.1-20.61 Container bci/openjdk:21.0.12.1-24.60 Container bci/openjdk:25.0.4.1-9.60 Container bci/python:3.6.15-84.56 Container bci/python:latest Container suse/sle15:15.7-5.23.43 Affected
Container private-registry/1.2/harbor-core:1.2.1-1.115 Container private-registry/1.2/harbor-exporter:1.2.1-1.115 Container private-registry/1.2/harbor-jobservice:1.2.1-1.113 Container private-registry/1.2/harbor-registry:1.2.1-1.115 Container private-registry/1.2/harbor-registryctl:1.2.1-1.115 Container private-registry/1.2/harbor-trivy-adapter:1.2.1-1.124 Container private-registry/harbor-core:latest Container private-registry/harbor-exporter:latest Container private-registry/harbor-jobservice:latest Container private-registry/harbor-registry:2.8.3-1.85 Container private-registry/harbor-registryctl:latest Container private-registry/harbor-trivy-adapter:0.35.1-1.87 Container suse/kiosk/tigervnc-x11vnc:1.14-63.43 Container suse/mariadb:11.8.8-79.42 Affected
Container private-registry/1.2/harbor-portal:1.2.1-1.124 Container private-registry/harbor-portal:latest Container suse/kea:2.6-80.9 Container suse/kiosk/firefox-esr:153.3-75.45 Container suse/kiosk/pulseaudio:17.0-73.42 Container suse/kiosk/xorg-client:21-81.7 Container suse/kiosk/xorg:21.1-83.42 Container suse/mariadb-client:11.8.8-72.32 Container suse/postgres:16.15-93.41 Container suse/postgres:16.15-contrib-93.41 Container suse/postgres:17.11-83.40 Container suse/postgres:17.11-contrib-83.40 Container suse/postgres:18.6-73.40 Container suse/rmt-server:3.1-72.2 Container suse/samba-client:4.21-75.34 Container suse/samba-server:4.21-76.36 Container suse/samba-toolbox:4.21-76.34 Container third-party/amd/amdgpu-driver:sles-15.7-30.20.1 Container third-party/amd/amdgpu-driver:sles-15.7-30.30.4 Container third-party/amd/amdgpu-driver:sles-15.7-31.10 Container third-party/amd/amdgpu-driver:sles-15.7-31.20 Container third-party/amd/amdgpu-driver:sles-15.7-31.30 Container third-party/amd/amdgpu-driver:sles-15.7-31.40.1 Container third-party/amd/amdgpu-driver:sles-15.7-31.50 Container third-party/nvidia/driver:550-sles15.7 Container third-party/nvidia/driver:570-sles15.7 Container third-party/nvidia/driver:575-sles15.7 Container third-party/nvidia/driver:580-sles15.7 Container third-party/nvidia/driver:590-sles15.7 Container third-party/nvidia/driver:595-sles15.7 Container third-party/nvidia/driver:610-sles15.7 Affected
Container suse/ltss/sle15.5/sle15:15.5-8.73 Affected
Container suse/ltss/sle15.6/bci-base-fips:15.6-35.106 Affected

References

Advisories & patches
ADVISORY https://access.redhat.com/errata/RHSA-2026:74162 ADVISORY https://access.redhat.com/errata/RHSA-2026:74166 ADVISORY https://github.com/openssl/openssl/releases/tag/openssl-4.0.3 ADVISORY https://nvd.nist.gov/vuln/detail/CVE-2026-35189 ADVISORY https://seclists.org/oss-sec/2026/q3/1001 ADVISORY https://ubuntu.com/security/notices/USN-8847-1 ADVISORY https://vuldb.com/vuln/411430 ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:4412/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:4413/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:4414/ ADVISORY https://www.suse.com/support/update/SUSE-SU-2026:4419/ REF https://github.com/openssl/openssl/commit/2b93c73b2c70ddc4c61c5e4bfaaa6bd71379eb84 REF https://github.com/openssl/openssl/commit/3842516cc15e8b2cf55747011045e77547e71d89 REF https://github.com/openssl/openssl/commit/8e0efc7549b7ff8246d40e585e3fd604f728473f REF https://github.com/openssl/openssl/commit/c72ae182cac17a82e4246c6ecd4e9c4ec3586ec9 REF https://openssl-library.org/news/secadv/20260929.txt

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