CVE-2026-101955

Junos OS: SRX Series: Malformed DNS packet causes service disruption when UTM Anti-Spam SBL is used

Published Oct 14, 2026 CVSS 4.0 · 9.2 Critical EPSS < 1% KEV · Not listed
Description
A Stack-based Buffer Overflow vulnerability in the UTM Anti-Spam SBL of Juniper Networks Junos OS on SRX series allows an unauthenticated remote attacker to cause arbitrary code execution or a denial of service via a injected malformed DNS packet when Anti-Spam SBL inspection is enabled.

Remediation

Vendor Solution

The following software releases have been updated to resolve this specific issue: Junos OS: 23.2R2-S7.7, 23.4R2-S8.13, 24.2R2-S5.5, 24.4R2-S5, 25.2R2-S2, 25.4R1-S3, 25.4R2, 26.2R1-S2, 26.2R2, 26.4R1, and all subsequent releases. Note: For Junos OS releases 23.2, 23.4, and 24.2, specific respins have been referenced. Previously published versions of these releases have been rebuilt to resolve the security vulnerabilities identified in this advisory.


Vendor Workaround

There are no known workarounds for this issue.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Juniper Networks
Juniper Networks junos Os
Vendors & Products Juniper Networks
Juniper Networks junos Os
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A Stack-based Buffer Overflow vulnerability in the UTM Anti-Spam SBL of Juniper Networks Junos OS on SRX series allows an unauthenticated remote attacker to cause arbitrary code execution or a denial of service via a injected malformed DNS packet when Anti-Spam SBL inspection is enabled.
Title Junos OS: SRX Series: Malformed DNS packet causes service disruption when UTM Anti-Spam SBL is used
Weaknesses CWE-121
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 9.2, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:L'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
juniper
Published
Updated
Oct 16, 2026, 2:18 PM
Reserved
Sep 28, 2026, 4:28 PM
Status
Awaiting Analysis
Published
Oct 14, 2026, 5:17 PM
Modified
Oct 16, 2026, 3:16 PM