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Junos SpaceApplication · Juniper

CVE-2026-21907

MEDIUM · 5.9 CVSS v3.1 Published 2026-01-15
Fix available
A fix is available. Upgrade to 24.1 or later.
See remediation →
68/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The TLS/SSL server in Juniper Networks Junos Space allows the use of static key ciphers (ssl-static-key-ciphers), which do not provide Perfect Forward Secrecy (PFS). This vulnerability allows on-path attackers to potentially decrypt captured traffic, and compromises long-term confidentiality since compromising a static key allows decryption of all past sessions encrypted with that key.

MitigationDisable static key ciphers on the Junos Space TLS/SSL server and configure only PFS-enabled ciphers (ECDHE/DHE-based) to ensure forward secrecy. Upgrade to Junos Space 24.1R5 or later which addresses this vulnerability.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Junos SpaceApplication
Affected:< 24.1= 24.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Junos Space version
    Use the Junos Space web UI (Help > About) or CLI command 'show version' to determine the installed Junos Space version
    Affected if The installed version is any release prior to 24.1 or is exactly 24.1 (24.1.0 through 24.1R4)
  2. Locate TLS/SSL server configuration
    Access Junos Space web UI > Administration > TLS/SSL Settings, or check the SSL/TLS configuration files in the Junos Space configuration directory
    Affected if A TLS/SSL server configuration exists and is enabled for Junos Space services
  3. Inspect enabled cipher suites
    Review the configured cipher list in the TLS/SSL settings. Look for cipher strings containing 'static', 'aNULL', 'eNULL', or 'EXPORT' keywords, or specifically check if 'ssl-static-key-ciphers' is listed
    Affected if The enabled cipher list includes any static key ciphers that do not provide Perfect Forward Secrecy (non-ECDHE/non-DHE ciphers)
  4. Verify PFS capability
    Check whether all enabled cipher suites use ephemeral Diffie-Hellman (DHE) or elliptic curve Diffie-Hellman (ECDHE) key exchange
    Affected if At least one static key cipher is enabled and no PFS-capable ciphers are configured, or static key ciphers are prioritized

You are affected if your Junos Space version is < 24.1 or exactly 24.1 AND your TLS/SSL server configuration includes static key ciphers that lack Perfect Forward Secrecy.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 24.1 or later
Fixed in 24.1
Interim mitigation

Disable static key ciphers on the Junos Space TLS/SSL server and configure only PFS-enabled ciphers (ECDHE/DHE-based) to ensure forward secrecy. Upgrade to Junos Space 24.1R5 or later which addresses this vulnerability.

Recommended fix High confidence

24.1R5

  1. 1. Log into the Junos Space web interface or CLI
  2. 2. Navigate to the administration or system settings area
  3. 3. Locate the TLS/SSL configuration for the web server
  4. 4. Identify and remove any static key ciphers (ssl-static-key-ciphers) from the allowed cipher list
  5. 5. Ensure only modern, secure ciphers supporting Perfect Forward Secrecy (PFS) are enabled (e.g., TLS 1.2/1.3 with ECDHE or DHE cipher suites)
  6. 6. Apply the configuration changes
  7. 7. Restart the Junos Space services if required
  8. 8. Verify the changes by testing TLS/SSL connections to ensure only strong ciphers are accepted
Caveat Review release notes for any configuration or compatibility changes in 24.1R5 before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Junos Space Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-21907 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data