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No exploitation reported

CVE-2026-33846

Gnutls: gnutls: denial of service via heap buffer overflow in dtls handshake fragment reassembly

No exploitation reported by the sources we read.

  • Published2026-05-04
  • WeaknessCWE-130

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-05-0410:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 15:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-33846?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-33846?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • gnutlsAlmaLinux:10all versions · fixed in 3.8.10-4.el10_2and 5 other packages
  • gnutlsAlmaLinux:9all versions · fixed in 3.8.10-4.el9_8and 4 other packages
  • gnutlsAlmaLinux:8all versions · fixed in 3.6.16-8.el8_10.6and 4 other packages

Vendor advisories

  • CVE-2026-33846 Red Hat Product Security890 products fixed

    gnutls: GnuTLS: Denial of Service via heap buffer overflow in DTLS handshake fragment reassembly

  • RHSA-2026:82888 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.17.2

  • RHSA-2026:82857 Red Hat Product Security1 product fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2

  • RHSA-2026:82372 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2

  • RHSA-2026:82354 Red Hat Product Security4 products fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2

  • RHSA-2026:82347 Red Hat Product Security8 products fixed

    Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.18.2

30 more advisories

Full record on NVD

Fix

  1. Vendor fix Red Hat Product Security RHSA-2026:82888 · 1 productBefore applying this update, make sure all previously released errata relevant to your system have been applied. The steps to apply the upgraded images are different depending on the installation plan approval policy you used when installing the cert-manager Operator for Red Hat OpenShift. - If t…
  2. Vendor fix Red Hat Product Security RHSA-2026:74674 · 1 productFor more information visit https://access.redhat.com/errata/RHSA-2026:74674
  3. Vendor fix Red Hat Product Security RHSA-2026:65839 · 1 productFor OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  4. Vendor fix Red Hat Product Security RHSA-2026:59831 · 1 productFor OpenShift Container Platform 4.12 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  5. Vendor fix Red Hat Product Security RHSA-2026:60019 · 4 productsFor OpenShift Container Platform 4.17 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…
  6. Vendor fix Red Hat Product Security RHSA-2026:56853 · 4 productsFor OpenShift Container Platform 4.16 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2026-05-04
Last Modified
2026-10-14
NVD status
Awaiting Analysis
MSRC Title
Gnutls: gnutls: denial of service via heap buffer overflow in dtls handshake fragment reassembly

Frequently asked questions

What is CVE-2026-33846?

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.

Is CVE-2026-33846 actively exploited?

Active exploitation of CVE-2026-33846 has not been confirmed. Its EPSS score was 1.1% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-33846?

CVE-2026-33846 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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