Vulnerability · Published Jan 15, 2026 · Assigned by juniper

CVE-2026-21917Junos OS: SRX Series: Specifically malformed SSL packet causes FPC crash

High 7.5

In plain English

A high-severity security flaw in Junos OS from Juniper Networks. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 35% of all known vulnerabilities).

Severity (CVSS 3.1)7.5High

Exploit odds (30 days)0.4%top 64.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

An Improper Validation of Syntactic Correctness of Input vulnerability in the Web-Filtering module of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an SRX device configured for UTM Web-Filtering receives a specifically malformed SSL packet, this will cause an FPC crash and restart. This issue affects Junos OS on SRX Series: * 23.2 versions from 23.2R2-S2 before 23.2R2-S5, * 23.4 versions from 23.4R2-S1 before 23.4R2-S5, * 24.2 versions before 24.2R2-S2, * 24.4 versions before 24.4R1-S3, 24.4R2. Earlier versions of Junos are also affected, but no fix is available.

Affected products (as reported)

Vendor	Product	Versions
Juniper Networks	Junos OS	23.2R2-S2 – before 23.2R2-S523.4R2-S1 – before 23.4R2-S524.2 – before 24.2R2-S224.4 – before 24.4R1-S3, 24.4R2

Weakness: CWE-1286 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

https://supportportal.juniper.net/JSA105996 vendor-advisory
https://kb.juniper.net/JSA105996 vendor-advisory