CVE-2026-101990: A Stack-based Buffer Overflow vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS

Q: How do I fix CVE-2026-101990?

junos os evolved: upgrade to newer than 23.1; junos: upgrade to newer than 23.1. Exact commands for each OS are on this page.

Q: Is CVE-2026-101990 being exploited?

CVE-2026-101990 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-2026-101990 affect?

CVE-2026-101990 affects junos os evolved, junos. Severity is critical (CVSS 9.8). A Stack-based Buffer Overflow vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a remote configured BGP peer to cause an rpd crash, or on Junos OS remote code-execution, via sending

Q: How urgent is CVE-2026-101990?

Priority 51/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADEUPGRADE

CVE-2026-101990 is a critical-severity flaw (CVSS 9.8) affecting junos os evolved, junos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A Stack-based Buffer Overflow vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a remote configured BGP peer to cause an rpd crash, or on Junos OS remote code-execution, via sending a flow-spec update which is selected for re-advertisement.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-121
Published	2026-10-14
Last modified	2026-10-30

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

Last updated 2026-10-30 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-14 17:17 UTCPublished CVE record published
2026-10-30 18:42 UTCUpdated Record last modified

juniper junos os evolved UPGRADE

Affected: <= 23.1 · 23.2 · 23.2 r1 · 23.2 r1-s1 · 23.2 r1-s2 · 23.2 r2 · 23.2 r2-s1 · 23.2 r2-s2

Fixed in: newer than 23.1

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.

juniper junos UPGRADE

Affected: <= 23.1 · 23.2 · 23.2 r1 · 23.2 r1-s1 · 23.2 r1-s2 · 23.2 r2 · 23.2 r2-s1 · 23.2 r2-s2

Fixed in: newer than 23.1

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-2026-101990?

junos os evolved: upgrade to newer than 23.1; junos: upgrade to newer than 23.1. Exact commands for each OS are on this page.

Is CVE-2026-101990 being exploited?

CVE-2026-101990 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-2026-101990 affect?

CVE-2026-101990 affects junos os evolved, junos. Severity is critical (CVSS 9.8). A Stack-based Buffer Overflow vulnerability in the routing protocol daemon (rpd) of Juniper Networks Junos OS and Junos OS Evolved allows a remote configured BGP peer to cause an rpd crash, or on Junos OS remote code-execution, via sending

How urgent is CVE-2026-101990?

Priority 51/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

Juniper Junos vulnerabilities

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References

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