Cyber Resilience

CVE-2026-33778

Juniper Junos ≤ 22.4

Published
09 April 2026
Modified
17 April 2026
Patch / advisory
View advisory
CVSS Score v4 8.7
Click a component to see what it means
Raw vectorCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:Y/R:X/V:X/RE:M/U:X
EPSS Score 0.0034 27th percentile
Risk Priority 44 floored blend · peak EPSS

Summary

CVE-2026-33778 is a high-severity Improper Validation of Syntactic Correctness of Input (CWE-1286) vulnerability in Juniper Junos. Its CVSS base score is 8.7 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 27th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) — see the control section below for these in your framework.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

CVE-2026-33778 is an Improper Validation of Syntactic Correctness of Input vulnerability (CWE-1286) in the IPsec library used by the kmd and iked processes within Juniper Networks Junos OS on SRX Series and MX Series devices. It affects all versions prior to 22.4R3-S9, 23.2 versions before 23.2R2-S6, 23.4 versions before 23.4R2-S7, 24.2 versions before 24.2R2-S4, 24.4 versions before 24.4R2-S3, and 25.2 versions before 25.2R1-S2 or 25.2R2. The issue, published on 2026-04-09, carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H), indicating high-impact availability disruption without requiring authentication or user interaction.

An unauthenticated, network-based attacker can exploit this vulnerability by sending a specifically malformed first ISAKMP packet to an affected device acting as a VPN responder. This triggers a crash and restart of the kmd or iked process, temporarily preventing the establishment of new IPsec security associations (SAs). Repeated exploitation sustains the denial-of-service condition, rendering the device unable to form new VPN connections and potentially disrupting ongoing network security operations.

Juniper's security advisory at https://kb.juniper.net/JSA107868 details mitigation through upgrading to patched Junos OS releases beyond the listed vulnerable versions, such as 22.4R3-S9 and later where applicable.

EU & UK References

Vulnerability Data

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).…

more

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.

CWE(s)
CWE-1286

Related Threats

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-57026Same product: Juniper Junos
CVE-2026-21917Same product: Juniper Junos
CVE-2023-28985Same product: Juniper Junos
CVE-2025-30656Same product: Juniper Junos
CVE-2025-52960Same product: Juniper Junos
CVE-2026-21918Same product: Juniper Junos
CVE-2024-21616Same product: Juniper Junos
CVE-2024-39542Same product: Juniper Junos
CVE-2024-21598Same product: Juniper Junos
CVE-2024-21595Same product: Juniper Junos

Affected Assets

juniper
junos
22.4, 23.2, 23.4, 24.2, 24.4 · ≤ 22.4

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)

—

Validate
Prove the fix (OWASP ASVS)
  • V1.1.1
  • V1.4.2
  • V2.1.1
  • V2.2.2

Mitigating Controls (NIST 800-53 r5) AI

SI-10 Information Input Validation good match

SI-10 requires validation of information inputs for correctness, directly stopping syntactic validation failures from being introduced or exploitable.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 mostly match
prevents

Secure SDLC practices directly require syntactic input validation to prevent malformed data handling.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches missing or incorrect syntax validation.

A.8.25 Secure development life cycle partial match
prevents

Secure development life cycle mandates input validation to ensure syntactic correctness.

A.8.26 Application security requirements partial match
prevents

Application security requirements explicitly call for validation of input syntax.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles reduce the likelihood of missing syntactic checks.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly require proper syntactic validation of all inputs.

References