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CVE-2026-33846

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

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Red Hat / Red Hat Enterprise Linux 10unaffected 0:3.8.10-4.el10_2 before *
Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Supportunaffected 0:3.8.9-9.el10_0.19 before *
Red Hat / Red Hat Enterprise Linux 7 Extended Lifecycle Supportunaffected 0:3.3.29-9.el7_9.1 before *
Red Hat / Red Hat Enterprise Linux 8unaffected 0:3.6.16-8.el8_10.6 before *
Red Hat / Red Hat Enterprise Linux 8unaffected 0:3.6.16-8.el8_10.6 before *
Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportunaffected 0:3.6.14-10.el8_4.1 before *
Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Supportunaffected 0:4.13-3.el8_4.1 before *
Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onunaffected 0:3.6.14-10.el8_4.1 before *
Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-Onunaffected 0:4.13-3.el8_4.1 before *
Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportunaffected 0:3.6.16-5.el8_6.5 before *
Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportunaffected 0:4.13-3.el8_6.2 before *
Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Onunaffected 0:3.6.16-5.el8_6.5 before *
Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Onunaffected 0:4.13-3.el8_6.2 before *
Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Serviceunaffected 0:3.6.16-7.el8_8.4 before *
Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Serviceunaffected 0:4.13-4.el8_8.1 before *
Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutionsunaffected 0:3.6.16-7.el8_8.4 before *
Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutionsunaffected 0:4.13-4.el8_8.1 before *
Red Hat / Red Hat Enterprise Linux 9unaffected 0:3.8.10-4.el9_8 before *
Red Hat / Red Hat Enterprise Linux 9unaffected 0:3.8.10-4.el9_8 before *
Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutionsunaffected 0:3.7.6-21.el9_2.7 before *
Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutionsunaffected 0:3.8.3-4.el9_4.6 before *
Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Supportunaffected 0:3.8.3-6.el9_6.4 before *
Red Hat / Red Hat OpenShift Container Platform 4.12unaffected 412.86.202608241157-0 before *
Red Hat / Red Hat OpenShift Container Platform 4.13unaffected 413.92.202609080414-0 before *
Red Hat / Red Hat OpenShift Container Platform 4.14unaffected 414.92.202608172040-0 before *
Red Hat / Red Hat OpenShift Container Platform 4.15unaffected 415.92.202608180329-0 before *
Red Hat / Red Hat OpenShift Container Platform 4.16unaffected 416.94.202608150307-0 before *
Red Hat / Red Hat OpenShift Container Platform 4.17unaffected 417.94.202608250221-0 before *
Red Hat / Red Hat OpenShift Container Platform 4.18unaffected 418.94.202608142238-0 before *
Red Hat / Red Hat OpenShift Container Platform 4.19unaffected 4.19.9.6.202608182320-0 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.17unaffected 1791371080 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.17unaffected 1791371069 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.17unaffected 1791788287 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.17unaffected 1791970484 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.18unaffected 1791459707 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.18unaffected 1791459711 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.18unaffected 1791459759 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.18unaffected 1789029076 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.18unaffected 1791966259 before *
Red Hat / Cert Manager support for Red Hat OpenShift release 1.20unaffected 1790598593 before *
Red Hat / Red Hat AI Inference Server 3.2unaffected 1782951051 before *
Red Hat / Red Hat AI Inference Server 3.2unaffected 1782951012 before *
Red Hat / Red Hat AI Inference Server 3.2unaffected 1782951244 before *
Red Hat / Red Hat Discovery 2unaffected 1782159791 before *
Red Hat / Red Hat Discovery 2unaffected 1782166952 before *
Red Hat / Red Hat Hardened Imagesunaffected 3.8.13-1.hum1 before *
Red Hat / Red Hat OpenShift AI 3.4unaffected 1790703542 before *
Red Hat / Red Hat Update Infrastructure 5unaffected 1781525684 before *
Red Hat / Red Hat Update Infrastructure 5unaffected 1781525671 before *
Red Hat / Red Hat Update Infrastructure 5unaffected 1781525693 before *
Red Hat / Red Hat Update Infrastructure 5unaffected 1781525739 before *
Red Hat / Red Hat Update Infrastructure 5unaffected 1787241211 before *
Red Hat / Red Hat Update Infrastructure 5unaffected 1787135742 before *
Red Hat / Red Hat Update Infrastructure 5unaffected 1787241260 before *
Red Hat / Red Hat Enterprise Linux 6unaffected
Red Hat / Red Hat OpenShift Container Platform 4unknown

CWE

CWE-130

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.

redhat-SADP

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.