CVE-2026-33800: An Unchecked Input for Loop Condition vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks

Q: How do I fix CVE-2026-33800?

junos: upgrade to 23.2. Exact commands for each OS are on this page.

Q: Is CVE-2026-33800 being exploited?

CVE-2026-33800 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-33800 affect?

CVE-2026-33800 affects junos. Severity is medium (CVSS 6.5). An Unchecked Input for Loop Condition vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS).Micro-BFD session flaps gene

Q: How urgent is CVE-2026-33800?

Priority 27/100. No elevated risk signals yet.

Routine

MEDIUM 6.5UPGRADE

CVE-2026-33800 is a medium-severity flaw (CVSS 6.5) affecting junos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An Unchecked Input for Loop Condition vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS).Micro-BFD session flaps generate respective up/down events which are queued by PFEMAN for processing. Especially in a Virtual-Chassis (VC) scenario with locality‑bias configured, processing takes a significant amount of time for each even

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 81%)
CISA exploited list	No
Weakness	CWE-606
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 21:16 UTCPublished CVE record published
2026-10-25 17:10 UTCUpdated Record last modified

juniper junos UPGRADE

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: 23.2

Safe to downgrade to: no unaffected older release

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-2026-33800?

junos: upgrade to 23.2. Exact commands for each OS are on this page.

Is CVE-2026-33800 being exploited?

CVE-2026-33800 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-2026-33800 affect?

CVE-2026-33800 affects junos. Severity is medium (CVSS 6.5). An Unchecked Input for Loop Condition vulnerability in the Packet Forwarding Engine (pfe) of Juniper Networks Junos OS on MX Series allows an unauthenticated, adjacent attacker to cause a Denial-of-Service (DoS).Micro-BFD session flaps gene

How urgent is CVE-2026-33800?

Priority 27/100. No elevated risk signals yet.

Software pages

Juniper Junos vulnerabilities

Related CVEs

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References

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