Skip to main content
View

Attack ChainAIDerived

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

  1. Access
    Send initial DTLS handshake fragment with small message_length
  2. Delivery
    Trigger heap buffer allocation sized to initial fragment
  3. Exploit
    Send subsequent fragments with inflated message_length values
  4. Execution
    Overflow allocated buffer during merge operation
  5. Persist
    Corrupt heap metadata or adjacent structures
  6. Impact
    Crash application or achieve memory corruption

Vulnerability Assessment

Weakness
CWE
CWE-130
ASVS 5.0
V15 - Secure Coding and Architecture Length parameter validation
Exploitation Conditions

Requires target system running GnuTLS library with DTLS protocol enabled and accessible over the network. The vulnerability is triggered during DTLS handshake fragment reassembly in merge_handshake_packet(), meaning any service accepting DTLS connections is exploitable. No authentication, user interaction, or non-default configuration required per CVSS vector AV:N/AC:L/PR:N/UI:N - remote unauthenticated exploitation against default DTLS configurations of GnuTLS. Services using only TLS over TCP (not DTLS over UDP) are not affected as they do not invoke the vulnerable fragment reassembly logic. The attack requires ability to send UDP datagrams to the target's DTLS port, which may be limited by network firewalls or NAT configurations but is otherwise unrestricted.
Impact

The CVSS 7.5 score (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) accurately reflects a remotely exploitable denial-of-service vulnerability requiring no authentication or user interaction. The High availability impact (A:H) is confirmed, while confidentiality and integrity impacts are rated None based on the scoring vector. However, heap buffer overflows classified as CWE-130 historically enable memory corruption beyond simple crashes - the description explicitly mentions 'potential memory corruption' which could theoretically escalate to code execution, though this remains unconfirmed. No EPSS score provided limits quantitative exploitation probability assessment. Absence from CISA KEV and no reported POC suggest exploitation is not yet widespread, but the technical simplicity (AC:L, no authentication) and prevalence of GnuTLS in server infrastructure make this attractive for targeted attacks. Real-world risk is elevated for internet-facing services using DTLS (VPN gateways, WebRTC servers, IoT devices) but lower for systems using only TLS over TCP or where DTLS is disabled. The vulnerability affects multiple RHEL major versions (6-10) indicating long-standing code, raising concerns about exposure window in production deployments. Missing data: exact vulnerable GnuTLS version ranges, confirmed fix version, independent vendor advisory beyond Red Hat.
Exploit ScenarioDerived

An attacker identifies a public-facing VPN gateway or WebRTC server using GnuTLS for DTLS connections. They initiate a DTLS handshake and send a crafted ClientHello fragment with message_length set to 256 bytes, causing GnuTLS to allocate a 256-byte heap buffer. The attacker then sends subsequent fragments of the same handshake message with message_length values of 2048 bytes containing attacker-controlled data. The merge_handshake_packet() function writes this data into the undersized buffer, corrupting adjacent heap structures and causing the service to crash (denial of service) or potentially enabling memory manipulation for further exploitation.
This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.1% exploitation probability (EPSS)

Get an e-mail when this CVE is exploited, patched or re-scored. Free account.

Alert me

AnalysisAIv1 – May 04, 2026

Heap buffer overflow in GnuTLS DTLS handshake allows remote unauthenticated attackers to crash applications or corrupt memory. The vulnerability stems from inconsistent fragment validation in merge_handshake_packet(), where attackers can send crafted DTLS fragments with conflicting message_length values to trigger out-of-bounds writes. Red Hat reported this affecting RHEL 6-10 and OpenShift Container Platform 4. CVSS 7.5 (High) reflects network-accessible denial of service, though memory corruption may enable further exploitation. No EPSS data, KEV status, or POC availability reported at time of analysis, but the remote unauthenticated attack vector (AV:N/PR:N) and low complexity (AC:L) make this a priority for systems using DTLS.

RemediationAI

Apply vendor-released security updates for GnuTLS as soon as Red Hat publishes patched packages for affected RHEL versions (consult https://access.redhat.com/security/cve/CVE-2026-33846 for release schedule and exact package versions). Until patches are deployed, implement compensating controls: disable DTLS protocol support entirely if not operationally required (configure applications to use TLS over TCP only), which eliminates the vulnerable code path but prevents UDP-based secure communications. For services that require DTLS, restrict network access to trusted IP ranges via firewall rules (note: this only reduces attack surface, does not eliminate vulnerability for permitted sources). Deploy network-layer DTLS traffic inspection if available to detect malformed handshake fragments, though evasion is likely given the protocol-level nature of the flaw. Monitor for application crashes in GnuTLS-dependent services as potential exploitation indicator. Prioritize patching for internet-facing DTLS endpoints (VPN concentrators, WebRTC gateways) over internal-only deployments.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Sign in to check
Technical ContextAI · show details

GnuTLS is a widely-deployed open-source TLS/DTLS library used across Linux distributions and applications for secure communications. DTLS (Datagram TLS) adapts TLS for UDP transport and handles fragmented handshake messages that may arrive out-of-order or duplicated. The vulnerable merge_handshake_packet() function matches fragments solely by handshake type (e.g., ClientHello, ServerHello) without enforcing that all fragments of a single logical message declare the same message_length field. This CWE-130 (Improper Handling of Length Parameter Inconsistency) allows an attacker to send an initial fragment with a small message_length (triggering allocation of a correspondingly small heap buffer), followed by additional fragments with larger message_length values. When these inconsistent fragments are merged, data is written beyond the allocated buffer bounds, resulting in heap corruption. The affected CPE entries indicate Red Hat Enterprise Linux versions 6 through 10, Red Hat Hardened Images, and OpenShift Container Platform 4 all package vulnerable GnuTLS versions.

Know when Red Hat Enterprise Linux 10 gets its next vulnerability

  • Watch products and get an email when something new is published
  • Check this CVE against your own stack and servers
  • Exploit and PoC references, threat intelligence from 22 sources
Continue with Google Continue with GitHub

No credit card · 7-day full trial

Severity by source

Vendor (redhat) PRIMARY 7.5 HIGH
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SUSE HIGH
Red Hat 7.5 HIGH

Primary rating from Vendor (redhat).

CVSS VectorVendor: redhat

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

DescriptionCVE.org

A heap buffer overflow vulnerability exists in the DTLS handshake fragment reassembly logic of GnuTLS. The issue arises in merge_handshake_packet() where incoming handshake fragments are matched and merged based solely on handshake type, without validating that the message_length field remains consistent across all fragments of the same logical message. An attacker can exploit this by sending crafted DTLS fragments with conflicting message_length values, causing the implementation to allocate a buffer based on a smaller initial fragment and subsequently write beyond its bounds using larger, inconsistent fragments. Because the merge operation does not enforce proper bounds checking against the allocated buffer size, this results in an out-of-bounds write on the heap. The vulnerability is remotely exploitable without authentication via the DTLS handshake path and can lead to application crashes or potential memory corruption.

Executive ViewAI

Why It Matters

CVE-2026-33846 is a heap buffer overflow in GnuTLS DTLS handshake processing that allows remote attackers to crash applications or corrupt memory without authentication. Organizations running RHEL 6-10, OpenShift Container Platform 4, or any systems dependent on vulnerable GnuTLS versions face immediate denial-of-service risk and potential for escalated attacks through memory corruption. This requires urgent assessment and mitigation given the network-accessible attack vector and lack of available patches.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: (1) Disable DTLS protocol if not operationally required; (2) Implement network-level access controls restricting DTLS traffic (UDP port 443 or custom DTLS ports) to trusted internal or VPN-only sources; (3) Deploy Web Application Firewalls or DDoS mitigation to absorb denial-of-service attempts; (4) Monitor system logs for DTLS handshake errors or unexpected process crashes; (5) Maintain current backups and establish automated restart policies for crash resilience. These controls reduce attack surface but do not eliminate the underlying vulnerability-patch application upon release is mandatory.

Threat Intelligence Overview

EPSS Score
0.1%
Top 82% exploitable
Social Media
2
Sightings
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment MSRC Vendor CIRCL 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 HIGH
CISA KEV No
Public POC No
EPSS 0.1%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
Yes
Human Impact
High
Technical Impact
Partial

Priority Score

38
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Affected Products (CPE)CVE.org

cpe:2.3:a:red_hat:red_hat_enterprise_linux_10:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_6:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_7:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_8:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_enterprise_linux_9:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_hardened_images:*:*:*:*:*:*:*:*
cpe:2.3:a:red_hat:red_hat_openshift_container_platform_4:*:*:*:*:*:*:*:*

More in Red Hat Enterprise Linux 10

View all
CVE-2026-18663 MEDIUM
5.9 Aug 12

Heap corruption via double-free in 389-ds-base's LDAP control parsing allows an unauthenticated remote attacker to crash
CVE-2026-4631 CRITICAL POC
9.8 Apr 07

Remote code execution in Cockpit's web interface allows unauthenticated attackers to execute arbitrary commands on the h
CVE-2026-4480 CRITICAL POC
9.0 May 26

Remote code execution in Samba's printing subsystem allows remote attackers to inject arbitrary shell commands via craft
CVE-2026-101258 HIGH POC
7.8 Oct 06

Ghostscript can execute arbitrary shell commands with the privileges of its process when it renders a crafted PostScript
CVE-2026-96889 HIGH POC
7.8 Sep 23

Use-after-free in librsvg during rendering of crafted SVG documents with nested XInclude directives and duplicate entity
CVE-2026-4775 HIGH POC
7.8 Mar 24

A signed integer overflow vulnerability exists in the libtiff library's putcontig8bitYCbCr44tile function that leads to

CVE-2026-114406 MEDIUM POC
6.8 Oct 21

The system CA trust store shipped in Red Hat's ca-certificates RPM packages includes eMudhra root authorities that signe
CVE-2026-18922 CRITICAL
9.8 Sep 07

Authentication bypass in 389 Directory Server (shipped as Red Hat Directory Server 11-13 and within RHEL 6-10) lets remo
CVE-2026-14544 CRITICAL
9.8 Jul 03

Remote code execution and privilege escalation in HPLIP (HP Linux Imaging and Printing) affects the hpcups print filter

CVE-2026-76578 CRITICAL
9.8 Sep 07

Unauthenticated privilege escalation in FreeIPA (Red Hat Identity Management) allows a remote attacker to gain genuine a
CVE-2026-102560 CRITICAL
9.8 Sep 29

A heap buffer overflow exists in libsoup's WebSocket permessage-deflate compression path: when a very large outbound mes
CVE-2026-5121 HIGH
7.5 Mar 30

Remote code execution in libarchive on 32-bit systems allows unauthenticated attackers to execute arbitrary code via spe

Same weakness CWE-130 – Improper Handling of Length Parameter Inconsistency

View all
CVE-2026-109390 CRITICAL POC
9.8
CVE-2022-1543 HIGH POC
8.8
CVE-2022-3290 HIGH POC
7.5
CVE-2022-3272 HIGH POC
7.5
CVE-2026-114597 HIGH
8.7
CVE-2019-3862 CRITICAL
9.1
CVE-2021-36090 HIGH
7.5
CVE-2022-2714 CRITICAL
9.8

Same technique Buffer Overflow

View all
CVE-2017-7269 CRITICAL POC
9.8
CVE-2015-5119 CRITICAL POC
9.8
CVE-2015-3113 CRITICAL POC
9.8
CVE-2011-2462 CRITICAL POC
9.8
CVE-2020-0796 CRITICAL POC
10.0
CVE-2019-11043 CRITICAL POC
9.8
CVE-2009-0927 HIGH POC
8.8
CVE-2012-1889 HIGH POC
8.8

Vendor StatusVendor

SUSE

Severity: High
Product Status
openSUSE Tumbleweed Fixed
SUSE Linux Enterprise Desktop 15 SP7 Fixed
SUSE Linux Enterprise High Performance Computing 15 SP7 Fixed
SUSE Linux Enterprise Micro 5.3 Fixed
SUSE Linux Enterprise Micro 5.4 Fixed

References

Advisories & patches
ADVISORY https://ubuntu.com/security/notices/USN-8284-1 ADVISORY https://vuldb.com/vuln/360952 REF https://access.redhat.com/errata/RHSA-2026:13274 REF https://access.redhat.com/errata/RHSA-2026:20611 REF https://access.redhat.com/errata/RHSA-2026:20612 REF https://access.redhat.com/errata/RHSA-2026:20613 REF https://access.redhat.com/errata/RHSA-2026:26319 REF https://access.redhat.com/errata/RHSA-2026:26409 REF https://access.redhat.com/errata/RHSA-2026:29197 REF https://access.redhat.com/errata/RHSA-2026:30004 REF https://access.redhat.com/errata/RHSA-2026:30849 REF https://access.redhat.com/errata/RHSA-2026:30850 REF https://access.redhat.com/errata/RHSA-2026:32962 REF https://access.redhat.com/errata/RHSA-2026:33125 REF https://access.redhat.com/errata/RHSA-2026:34372 REF https://access.redhat.com/errata/RHSA-2026:36004 REF https://access.redhat.com/errata/RHSA-2026:36005 REF https://access.redhat.com/errata/RHSA-2026:36006 REF https://access.redhat.com/errata/RHSA-2026:41921 REF https://access.redhat.com/errata/RHSA-2026:56786 REF https://access.redhat.com/errata/RHSA-2026:56853 REF https://access.redhat.com/errata/RHSA-2026:56911 REF https://access.redhat.com/errata/RHSA-2026:57402 REF https://access.redhat.com/errata/RHSA-2026:57483 REF https://access.redhat.com/errata/RHSA-2026:58981 REF https://access.redhat.com/errata/RHSA-2026:59831 REF https://access.redhat.com/errata/RHSA-2026:60019 REF https://access.redhat.com/errata/RHSA-2026:65839 REF https://access.redhat.com/errata/RHSA-2026:72502 REF https://access.redhat.com/errata/RHSA-2026:74674 REF https://access.redhat.com/errata/RHSA-2026:82304 REF https://access.redhat.com/errata/RHSA-2026:82322 REF https://access.redhat.com/errata/RHSA-2026:82347 REF https://access.redhat.com/errata/RHSA-2026:82354 REF https://access.redhat.com/errata/RHSA-2026:82372 REF https://access.redhat.com/errata/RHSA-2026:82857 REF https://access.redhat.com/errata/RHSA-2026:82888 REF https://access.redhat.com/security/cve/CVE-2026-33846 REF https://bugzilla.redhat.com/show_bug.cgi?id=2450625 REF https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33846.json

Search Externally

GitHub PoC Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC
Back

This site uses cookies essential for authentication and security. No tracking or analytics cookies are used. Privacy Policy