CVE-2026-101955 PUBLISHED

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

Assigner: juniper
Reserved: 28.09.2026 Published: 14.10.2026 Updated: 14.10.2026

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.

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS Score: 8.1

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

CVSS 3.1

CVSS 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
CVSS Score: 9.2

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	High	Confidentiality	None
Attack Complexity	Low	Integrity	High	Integrity	None
Attack Requirements	Present	Availability	High	Availability	Low
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	Juniper Networks
Product	Junos OS
Versions	Default: unaffected affected from 0 to 23.2R2-S7.7 (excl.) affected from 23.4 to 23.4R2-S8.13 (excl.) affected from 24.2 to 24.2R2-S5.5 (excl.) affected from 24.4 to 24.4R2-S5 (excl.) affected from 25.2 to 25.2R2-S2 (excl.) affected from 25.4 to 25.4R1-S3 (excl.) affected from 26.2 to 26.2R1-S2 (excl.)

Affected Configurations

[ security utm default-configuration anti-spam type sbl ]

Exploits

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

Workarounds

There are no known workarounds for this issue.

Solutions

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.

References

https://supportportal.juniper.net/JSA112186

Problem Types

CWE-121 Stack-based Buffer Overflow CWE