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OpenSSL EUVDEUVD-2026-89011

| CVE-2026-75806 MEDIUM
Improper Validation of Specified Quantity in Input (CWE-1284)
2026-09-29 GHSA-4h8f-fwpc-hwwf
OpenSSL
5.3
CVSS 3.1 · Vendor
View

Attack ChainAIDerived

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

  1. Access
    Reach DTLS 1.2 listener over network
  2. Delivery
    Craft undersized AEAD record
  3. Exploit
    Send malformed datagram to endpoint
  4. Execution
    Trigger length mishandling in record layer
  5. Impact
    Denial-of-service on DTLS service

Vulnerability Assessment

Weakness
CWE
CWE-1284
ASVS 5.0
V2 - Validation and Business Logic Input size validation
Exploitation Conditions

The target must be an OpenSSL-based endpoint that accepts DTLS 1.2 connections using an AEAD ciphersuite (e.g., OpenVPN/DTLS-based VPNs, WebRTC/SRTP-DTLS media servers, SIP-over-DTLS, or CoAP/IoT DTLS services) running an affected version (OpenSSL 4.0.0<4.0.3, 3.6.0<3.6.5, 3.5.0<3.5.9, 3.4.0<3.4.8, 3.0.0<3.0.23, or 1.1.1<1.1.1zj). The attacker sends an unauthenticated, undersized DTLS 1.2 AEAD record to the datagram listener; no credentials or user interaction are required (PR:N/UI:N). The primary LIMITING factor is reachability: only DTLS deployments are affected - TLS-over-TCP (HTTPS) endpoints are not exposed to this datagram record-processing path - which sharply narrows the vulnerable population despite OpenSSL's ubiquity.
Impact

This is a genuine but low-to-moderate priority availability issue, not a high-severity emergency. The vendor CVSS 3.1 vector (5.3, AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L) is internally consistent with the description ('unauthenticated and undersized DTLS 1.2 AEAD record causing DoS') and with CWE-1284 (improper validation of a specified quantity/length in input): a malformed record triggers a denial-of-service with only low availability impact and no confidentiality or integrity impact. SSVC reinforces the modest priority - Exploitation: none (no observed exploitation), Automatable: yes (a single crafted datagram can be replayed, so mass automation is plausible), Technical Impact: partial (degradation/crash rather than total compromise). No EPSS score is provided, this CVE is NOT in CISA KEV, and no public exploit code is referenced. The one notable conflict is the input Tags labeling this 'Information Disclosure' - that is inconsistent with the vector (C:N) and the description, which describe a pure DoS; treat the DoS framing as authoritative. Net: a real, patch-worthy bug in a ubiquitous library, but bounded impact (A:L only, DTLS-only reachability) keeps real-world risk low-to-moderate rather than critical.
Exploit ScenarioDerived

An attacker positioned to send datagrams to a DTLS 1.2 endpoint (e.g., a VPN concentrator, WebRTC/SIP media server, or CoAP/IoT service using an AEAD ciphersuite) transmits a specially crafted undersized DTLS 1.2 AEAD record without needing authentication. The OpenSSL record layer mishandles the short record, causing a denial-of-service (crash or connection disruption). No public exploit is identified at time of analysis, but the low complexity (AC:L) and unauthenticated nature make it straightforward to weaponize once the packet format is known.
This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 29, 2026

Denial of service in OpenSSL's DTLS 1.2 record processing allows remote, unauthenticated attackers to disrupt affected endpoints by sending an undersized AEAD record that the library fails to validate properly. Only DTLS-over-datagram deployments are exposed - OpenSSL 4.0.0 through 4.0.2, 3.6.0 through 3.6.4, 3.5.0 through 3.5.8, 3.4.0 through 3.4.7, 3.0.0 through 3.0.22, and 1.1.1 through 1.1.1zi - while TLS-over-TCP services such as HTTPS do not traverse the vulnerable code path. Impact is limited to availability (CVSS 3.1 base 5.3, AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L); there is no public exploit identified at time of analysis, SSVC records exploitation as 'none', and the vendor has released fixed versions (notably OpenSSL 4.0.3, along with backports 3.6.5, 3.5.9, 3.4.8, 3.0.23 and 1.1.1zj).

RemediationAI

Upgrade to a fixed OpenSSL build: 4.0.3 on the 4.0 branch, or the corresponding backports 3.6.5, 3.5.9, 3.4.8, 3.0.23 and 1.1.1zj, as published in the vendor release notes at https://github.com/openssl/openssl/releases/tag/openssl-4.0.3 and the advisory at https://openssl-library.org/news/secadv/20260929.txt; because 4.0.3 bundles fifteen fixes including several other availability and side-channel issues (for example CVE-2026-84782 and CVE-2026-84783), patching to that release closes this CVE and its siblings in one step and should be prioritised over cherry-picking this single defect. Where patching must be staged, the highest-value compensating control is to stop exposing the DTLS datagram listener: terminate DTLS behind a TLS-over-TCP front end, disable DTLS cipher suites that use AEAD modes if the deployment can tolerate the loss of modern authenticated encryption, or restrict UDP access to known peer IP ranges at the firewall - the trade-off being that DTLS clients on dynamic addresses will be cut off and AEAD downgrades weaken confidentiality and integrity guarantees. For internet-facing UDP listeners that cannot be filtered, apply datagram rate limiting or a DTLS-aware reverse proxy/load balancer that drops malformed or anomalously short records before they reach OpenSSL, accepting the added latency and the risk that a distributed flood still degrades availability. Hosts used purely for TLS-over-TCP cannot reach the vulnerable code path, so they can be scheduled for routine patching rather than emergency change windows, but they should still be brought to the fixed version to pick up the other 4.0.3 fixes. Confirm the linked OpenSSL version (ldd/version string) in every DTLS-enabled service after upgrade, since static linking and vendored copies frequently leave the vulnerable build in place.

Affected VersionsENISA

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

Affected Packages

euvd openssl fix: 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

The flaw is classified as CWE-1284 (Improper Validation of Specified Quantity in Input) and lives in OpenSSL's DTLS 1.2 record layer handling of AEAD ciphersuites. DTLS runs over unreliable datagrams (UDP), so the record layer parses length and fragment fields from attacker-supplied packets before authentication and integrity checks can succeed; an undersized AEAD record supplies a quantity/length value that the implementation does not bound-check against the expected AEAD tag or ciphertext size, causing a processing failure that terminates or destabilises the connection-handling path. Because the trigger is an unauthenticated datagram arriving at the listener, no handshake completion, credential or user interaction is required (CVSS vector PR:N/UI:N). The vulnerable population is any OpenSSL-linked service that terminates DTLS 1.2 with an AEAD ciphersuite - for example OpenVPN and other DTLS-based VPN concentrators, WebRTC/SRTP-DTLS media servers, SIP-over-DTLS gateways and CoAP/IoT DTLS endpoints. TLS over TCP never enters this code path, which is the single most important scoping fact for triage. EUVD tracks this under EUVD-2026-89011 and lists the affected version ranges as OpenSSL 4.0.0 <4.0.3, 3.6.0 <3.6.5, 3.5.0 <3.5.9, 3.4.0 <3.4.8, 3.0.0 <3.0.23 and 1.1.1 <1.1.1zj. This CVE is one of fifteen security fixes shipped together in the OpenSSL 4.0.3 release, whose most severe item is rated High; the accompanying commit references in the NVD feed (04728a289a823e68137f88da016cb9ede307217d, 050b275cd671a6eed1d6457642d41a5a77aab972, 3a4589d015a9049d47b66f186cf50a8711343a1d, 5af82fefbaf2b5fec2fc0e1d87f112844902f01d) point to related changes in that batch and should not be assumed to map one-to-one onto this specific defect.

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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

Unauthenticated network-reachable DTLS endpoint (AV:N/PR:N/UI:N), low-complexity crafted record (AC:L), and DoS-only impact with no confidentiality or integrity effect (C:N/I:N/A:L).

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 5.3 MEDIUM

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 29, 2026 - 17:22 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
0.4%
Top 70% exploitable
Prevalence
Ubiquitous
OpenSSL is the default TLS/DTLS library across most Linux and networked software
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 0.4%
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

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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:3.13.15-88.58 Container bci/python:3.6.15-84.56 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/hpc/warewulf4-x86_64/sle-hpc-node:15.7.20.8.177 Container suse/kiosk/tigervnc-x11vnc:1.14-63.43 Container suse/mariadb:11.8.8-79.42 Image pr_15_7_1_0 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 Container third-party/nvidia/driver:615-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-2026-75806 ADVISORY https://seclists.org/oss-sec/2026/q3/1001 ADVISORY https://ubuntu.com/security/notices/USN-8847-1 ADVISORY https://vuldb.com/vuln/411441 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/04728a289a823e68137f88da016cb9ede307217d REF https://github.com/openssl/openssl/commit/050b275cd671a6eed1d6457642d41a5a77aab972 REF https://github.com/openssl/openssl/commit/3a4589d015a9049d47b66f186cf50a8711343a1d REF https://github.com/openssl/openssl/commit/5af82fefbaf2b5fec2fc0e1d87f112844902f01d REF https://openssl-library.org/news/secadv/20260929.txt

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