CVE-2026-21917
Junos OS: SRX Series: Specifically malformed SSL packet causes FPC crash
- State
- Published
- Severity
- 8.7 High
- Published
- Jan 15, 2026
- Updated
- Jan 15, 2026
- Reserved
- Jan 5, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.7 High | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/AU:Y/R:A/RE:M | juniper |
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | juniper |
Weaknesses
- CWE-1286 Improper Validation of Syntactic Correctness of Input
Affected Products
| Product | Versions |
|---|---|
Junos OSJuniper Networks |
|
References
- https://supportportal.juniper.net/JSA105996vendor-advisory
- https://kb.juniper.net/JSA105996vendor-advisory
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