CVE-2026-57021: An Out-of-bounds Write vulnerability in the http-gatekeeper (http-gk) of Juniper Networks Junos OS on SRX Seri

Routine

MEDIUM 5.3REMOTEMITIGATE

CVE-2026-57021 is a medium-severity flaw (CVSS 5.3) affecting junos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An Out-of-bounds Write vulnerability in the http-gatekeeper (http-gk) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an SRX Series device is configured for remote-access VPN with pre-logon compliance check, a network-based attacker sending specifically formatted requests can trigger an out of bounds write leading to an http-gk process crash. This crash leads to

Why this priority

Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-07-09
Last modified	2026-10-25

Publisher (CNA): Juniper Networks, Inc. · Vendor: juniper

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-09 22:17 UTCPublished CVE record published
2026-10-25 15:10 UTCUpdated Record last modified

juniper junos MITIGATE

Affected: 23.2 · 23.2 r1 · 23.2 r1-s1 · 23.2 r1-s2 · 23.2 r2 · 23.2 r2-s1 · 23.2 r2-s2 · 23.2 r2-s3

Fixed in: no fixed release known

Safe to downgrade to: a release before 23.2

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-57021?

junos: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-57021 being exploited?

CVE-2026-57021 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-57021 affect?

CVE-2026-57021 affects junos. Severity is medium (CVSS 5.3). An Out-of-bounds Write vulnerability in the http-gatekeeper (http-gk) of Juniper Networks Junos OS on SRX Series allows an unauthenticated, network-based attacker to cause a Denial-of-Service (DoS). If an SRX Series device is configured fo

How urgent is CVE-2026-57021?

Priority 34/100. Remotely exploitable, no login, no user action

Software pages

Juniper Junos vulnerabilities

Related CVEs

CVE-2026-33800 MEDIUM 6.5 UPGRADE An Unchecked Input for Loop Condition vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks
CVE-2026-33802 MEDIUM 5.5 MITIGATE A Missing Authorization vulnerability in the CLI of Juniper Networks Junos OS on EX Series allows a local, aut
CVE-2026-57023 HIGH 7.5 MITIGATE An Improper Validation of Specified Quantity in Input vulnerability in the TCP proxy plugin of Juniper Network
CVE-2026-57026 HIGH 7.5 UPGRADE An Improper Validation of Syntactic Correctness of Input vulnerability in the SIP plugin of Juniper Networks J
CVE-2026-57022 MEDIUM 5.9 UPGRADE An Improper Check for Unusual or Exceptional Conditions vulnerability in the Packet Forwarding Engine (PFE) of

References

← Back to latest CVEs