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CVE Record

CVE-2026-33845: Gnutls: gnutls: denial of service via dtls zero-length fragment

A flaw in GnuTLS DTLS handshake parsing allows malformed fragments with zero length and non-zero offset, leading to an integer underflow during reassembly and resulting in an out-of-bounds read. This issue is remotely exploitable and may cause information disclosure or denial of service.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-33845 affects GnuTLS handling of DTLS handshake fragments. A remote attacker could send malformed traffic that may crash affected services using DTLS. The provided CVSS rates availability impact high, with no privileges or user interaction required. No provided source indicates active exploitation or CISA KEV listing.

Executive priority

Treat as a near-term patching item for Linux infrastructure, especially externally reachable DTLS services. It is high severity due to remote, unauthenticated denial-of-service potential, but current provided evidence does not support emergency exploitation response.

Technical view

The flaw is an integer underflow in DTLS handshake reassembly when parsing a zero-length fragment with a non-zero offset, causing an out-of-bounds read. The CVSS vector is 7.5, network, low complexity, no privileges, no user interaction, availability high. The description mentions possible information disclosure, but the CVSS supplied marks confidentiality impact as none.

Likely exposure

Exposure is most likely on systems running affected Red Hat Enterprise Linux gnutls packages where applications use DTLS. The bundle lists affected RHEL 7 ELS, RHEL 8 variants, RHEL 9, and RHEL 10 streams. Some RHEL 8 entries also list libtasn1; confirm scope against Red Hat advisories.

Exploitation context

Remote exploitation is described as possible, but the provided sources do not show public exploitation, weaponized tooling, or KEV inclusion. Practical risk depends on whether DTLS-enabled services using GnuTLS are reachable by untrusted networks.

Researcher notes

Focus validation on DTLS-enabled code paths using GnuTLS. Note source inconsistency: the narrative says possible information disclosure, while the supplied CVSS vector has C:N. Do not assume confidentiality impact without vendor clarification. Use Red Hat CSAF/VEX and RHSA records for stream-specific status.

Mitigation direction

  • Identify systems with affected Red Hat gnutls packages and DTLS-facing services.
  • Apply the applicable Red Hat security advisories for each supported RHEL stream.
  • Prioritize internet-facing or partner-facing DTLS services first.
  • If updates are unavailable, check Red Hat guidance for supported workarounds.
  • Restart dependent services after package updates where required by vendor guidance.

Validation and detection

  • Inventory installed gnutls package versions across RHEL assets.
  • Map exposed services that use DTLS or GnuTLS libraries.
  • Check patch status against the relevant Red Hat RHSA advisory.
  • Review service stability logs for crashes around malformed DTLS traffic.
  • Confirm no affected package remains after remediation scans.
Prepared
Confidence
medium
Sources
9

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-191: Exact CWE lookup

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description · low confidence lookup

Container behavior lookup

The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2026-33845 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
7Timeline events
2ADP providers
20Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-33845Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Reported to Red Hat.

  3. Source timelineredhat

    Reported to Red Hat.

  4. ADP timelineredhat-SADP

    Made public.

  5. Source timelineredhat

    Made public.

  6. CVE publishedCVE Program

    The CVE record was published.

  7. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPgnutls: GnuTLS: Denial of Service via DTLS zero-length fragment
other:Red Hat severity ratingcvssV3_1
  • 2026-03-24T05:35:59.740Z: Reported to Red Hat.
  • 2026-04-30T17:28:41.473Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Unknown vendorgnutlsgnutls, 0unaffected
Red HatRed Hat Enterprise Linux 10gnutls, 0:3.8.10-4.el10_2affected
Red HatRed Hat Enterprise Linux 10.0 Extended Update Supportgnutls, 0:3.8.9-9.el10_0.19affected
Red HatRed Hat Enterprise Linux 7 Extended Lifecycle Supportgnutls, 0:3.3.29-9.el7_9.1affected
Red HatRed Hat Enterprise Linux 8gnutls, 0:3.6.16-8.el8_10.6affected
Red HatRed Hat Enterprise Linux 8gnutls, 0:3.6.16-8.el8_10.6affected
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportgnutls, 0:3.6.14-10.el8_4.1affected
Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportlibtasn1, 0:4.13-3.el8_4.1affected
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Ongnutls, 0:3.6.14-10.el8_4.1affected
Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onlibtasn1, 0:4.13-3.el8_4.1affected
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportgnutls, 0:3.6.16-5.el8_6.5affected
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportlibtasn1, 0:4.13-3.el8_6.2affected
Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Ongnutls, 0:3.6.16-5.el8_6.5affected
Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Onlibtasn1, 0:4.13-3.el8_6.2affected
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Servicegnutls, 0:3.6.16-7.el8_8.4affected
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Servicelibtasn1, 0:4.13-4.el8_8.1affected
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutionsgnutls, 0:3.6.16-7.el8_8.4affected
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutionslibtasn1, 0:4.13-4.el8_8.1affected
Red HatRed Hat Enterprise Linux 9gnutls, 0:3.8.10-4.el9_8affected
Red HatRed Hat Enterprise Linux 9gnutls, 0:3.8.10-4.el9_8affected
Red HatRed Hat Enterprise Linux 9.4 Update Services for SAP Solutionsgnutls, 0:3.8.3-4.el9_4.6affected
Red HatRed Hat Enterprise Linux 9.6 Extended Update Supportgnutls, 0:3.8.3-6.el9_6.4affected
Red HatRed Hat AI Inference Server 3.2rhaiis/model-opt-cuda-rhel9, 1782951051affected
Red HatRed Hat AI Inference Server 3.2rhaiis/vllm-cuda-rhel9, 1782951012affected
Red HatRed Hat AI Inference Server 3.2rhaiis/vllm-rocm-rhel9, 1782951244affected
Red HatRed Hat Discovery 2discovery/discovery-server-rhel9, 1782159791affected
Red HatRed Hat Discovery 2discovery/discovery-ui-rhel9, 1782166952affected
Red HatRed Hat Hardened Imagesgnutls-main, 3.8.13-1.hum1affected
Red HatRed Hat Update Infrastructure 5rhui5/cds-rhel9, 1781525684affected
Red HatRed Hat Update Infrastructure 5rhui5/haproxy-rhel9, 1781525671affected
Weakness

CWE details

CWE-191

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-191 · source CWE mapping

Integer Underflow (Wrap or Wraparound)

Integer Underflow (Wrap or Wraparound) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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