Medium Cryptography

CVE-2026-21907 — Junos Space: TLS/SSL server supports use of static key ciphers (ssl-static-key-ciphers)

A Use of a Broken or Risky Cryptographic Algorithm vulnerability in the TLS/SSL server of Juniper Networks Junos Space allows the use of static key ciphers (ssl-static-key-ciphers), reducing the confidentiality of on-path traffic communicated across the connection. These ciphers also do not support Perfect Forward Secrecy (PFS), affecting the long-term confidentiality of encrypted communications.This issue affects all versions of Junos Space before 24.1R5.

Published Jan 15, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: juniper

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+1
Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.2%

ahead of 9% of scored CVEs · Oct 14, 2026

Affects

Juniper Networks

Junos Space

CVSS base

5.9

Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Juniper Networks Junos Space).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Juniper Networks	Junos Space	< 24.1version 24.1-r1version 24.1-r2version 24.1-r3version 24.1-r4	Vulnerable	NIST National Vulnerability Database
Juniper Networks	Junos Space	< 24.1R5	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

High

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.2	CVSS 4.0	High	—	—	sirt@juniper.net via NIST National Vulnerability Database
8.2	CVSS 4.0	High	—	—	juniper via CVE Program (cve.org) e CISA ADP
5.9	CVSS 3.1	Medium	2.2	3.6	sirt@juniper.net via NIST National Vulnerability Database
5.9	CVSS 3.1	Medium	—	—	juniper via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N (score shown at the top: sirt@juniper.net)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-327 · Use of a Broken or Risky Cryptographic Algorithm

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.20%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Check TLS negotiations and unexpected certificates in the component’s traffic.

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · juniper networks/junos space
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 5.9
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Jan 15, 2026 · juniper

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

2 on the record

supportportal.juniper.net/JSA106006
Vendor Advisory, vendor-advisory, NIST National Vulnerability Database
kb.juniper.net/JSA106006
Vendor Advisory, vendor-advisory, NIST National Vulnerability Database

Elsewhere on this site

Juniper Networks
every CVE for this vendor

Cryptography
same class

CWE-327
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-21904 Junos Space: ilpFilter field on nLegacy.jsp is vulnerable to reflected cross-site script injection Apr 9, 2026
Medium CVE-2025-60009 Junos Space: CLI Configlet page is vulnerable to reflected cross-site script injection Oct 9, 2025
Medium CVE-2025-60001 Junos Space: Create Quick Template page is vulnerable to reflected cross-site script injection Oct 9, 2025
Medium CVE-2025-60000 Junos Space: Generate Report page is vulnerable to reflected cross-site script injection Oct 9, 2025
Medium CVE-2025-60002 Junos Space: Template Definitions page is vulnerable to reflected cross-site script injection Oct 9, 2025
Medium CVE-2025-59996 Junos Space: Configuration View page is vulnerable to reflected cross-site script injection Oct 9, 2025

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-21907 is "Junos Space: TLS/SSL server supports use of static key ciphers (ssl-static-key-ciphers)", rated Medium. It affects Junos Space (Juniper Networks); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.9 describes technical severity. EPSS 0.20% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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