NVD / CVE Program· CNA juniper

CVE-2024-21591: Junos OS: SRX Series and EX Series: Security Vulnerability in J-web allows a preAuth Remote Code Execution

Noroxi assessment

Priority: Plan (action score 44/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 17.6% (FIRST EPSS); higher than 97.1% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: Juniper Networks Junos OS 20.4R3-S9, 21.2R3-S7, 21.3R3-S5.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Add it to your regular patch cycle. Upgrade to Juniper Networks Junos OS 20.4R3-S9, 21.2R3-S7, 21.3R3-S5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

An Out-of-bounds Write vulnerability in J-Web of Juniper Networks Junos OS on SRX Series and EX Series allows an unauthenticated, network-based attacker to cause a Denial of Service (DoS), or Remote Code Execution (RCE) and obtain root privileges on the device. This issue is caused by use of an insecure function allowing an attacker to overwrite arbitrary memory. This issue affects Juniper Networks Junos OS SRX Series and EX Series: * Junos OS versions earlier than 20.4R3-S9; * Junos OS 21.2 versions earlier than 21.2R3-S7; * Junos OS 21.3 versions earlier than 21.3R3-S5; * Junos OS 21.4 versions earlier than 21.4R3-S5; * Junos OS 22.1 versions earlier than 22.1R3-S4; * Junos OS 22.2 versions earlier than 22.2R3-S3; * Junos OS 22.3 versions earlier than 22.3R3-S2; * Junos OS 22.4 versions earlier than 22.4R2-S2, 22.4R3.

CriticalCVSS 9.8 · v3.1—No exploit Fix available

BDU:2024-00263

Published: Jan 11, 2024
Updated: Jun 17, 2026
EPSS: 17.6% · 97th percentile
CWE: CWE-787

Report tools

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Action score

Plan

Add it to your regular patch cycle.

CVSS: 39 / 40 · 9.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 5 / 30 · 17.6%

CISA SSVC decision

Exploitation: none
Automatable: yes
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 9.8
CNA · juniper: 9.8; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
juniper	junos	cpe:2.3:o:juniper:junos

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

juniper junosbefore 20.4
juniper junos20.4
juniper junos21.2
juniper junos21.3
juniper junos21.4
juniper junos22.1
juniper junos22.2
juniper junos22.3
juniper junos22.4

Versions reported by the vendor

Affected version ranges reported by the assigning authority (juniper). Independent of NVD's CPE analysis and usually ahead of it.

Juniper Networks Junos OS
- before 20.4R3-S9affected · semver
- 21.2 and later · before 21.2R3-S7affected · semver
- 21.3 and later · before 21.3R3-S5affected · semver
- 21.4 and later · before 21.4R3-S5affected · semver
- 22.1 and later · before 22.1R3-S4affected · semver
- 22.2 and later · before 22.2R3-S3affected · semver
- 22.3 and later · before 22.3R3-S2affected · semver
- 22.4 and later · before 22.4R2-S2, 22.4R3affected · semver

Same product

juniper: all records

Other highest-scoring records for the same primary product.

CVE-2023-36845Junos OS: EX and SRX Series: A PHP vulnerability in J-Web allows an unauthenticated to control an important environment variableKEV
98Now
CVE-2023-36846Junos OS: SRX Series: A vulnerability in J-Web allows an unauthenticated attacker to upload arbitrary filesKEV
79This week
CVE-2023-36844Junos OS: EX Series: A PHP vulnerability in J-Web allows an unauthenticated attacker to control important environment variablesKEV
78This week

Published before and after this one in the same product

← EarlierCVE-2024-21585Jan 11, 2024 · Junos OS and Junos OS Evolved: BGP session flaps on NSR-enabled devices can cause rpd crash
23Monitor
← EarlierCVE-2024-21587Jan 11, 2024 · Junos OS: MX Series: Memory leak in bbe-smgd process if BFD liveness detection for DHCP subscribers is enabled
26Monitor
Later →CVE-2024-21594Jan 11, 2024 · Junos OS: SRX 5000 Series: Repeated execution of a specific CLI command causes a flowd crash
22Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Juniper Networks Junos OS	20.4R3-S9	Vendor (CNA)
Juniper Networks Junos OS	21.2R3-S7	Vendor (CNA)
Juniper Networks Junos OS	21.3R3-S5	Vendor (CNA)
Juniper Networks Junos OS	21.4R3-S5	Vendor (CNA)
Juniper Networks Junos OS	22.1R3-S4	Vendor (CNA)
Juniper Networks Junos OS	22.2R3-S3	Vendor (CNA)
Juniper Networks Junos OS	22.3R3-S2	Vendor (CNA)
Juniper Networks Junos OS	22.4R2-S2, 22.4R3	Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Marco LuxCuresec for responsibly reporting this vulnerabilityreporter

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2023-4419791 days apartJunos OS and Junos OS Evolved: An rpd crash may occur when BGP is processing newly learned routes
30Monitor
CVE-2023-22411364 days apartJunos OS: SRX Series: The flow processing daemon (flowd) will crash when Unified Policies are used with IPv6 and certain dynamic applications are rejected by th
30Monitor
CVE-2023-22415364 days apartJunos OS: MX Series and SRX Series: The flow processing daemon (flowd) will crash when specific H.323 packets are received
30Monitor
CVE-2023-22404364 days apartJunos OS: SRX Series and MX Series with SPC3: When IPsec VPN is configured iked will core when a specifically formatted payload is received
26Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).