How severe is CVE-2026-21907?

CVE-2026-21907 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-21907 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21907?

CVE-2026-21907 primarily affects Juniper Junos Space. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-21907?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-21907 have an EU (EUVD) identifier?

Yes. CVE-2026-21907 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2700.

When was CVE-2026-21907 published?

CVE-2026-21907 was published on 2026-01-15 and last updated on 2026-06-17.

CVE-2026-21907

CVE-2026-21907 is a medium-severity vulnerability in Juniper Junos Space with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-327.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v4: 8.2
EPSS exploit prediction: 0% (8th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-2700
Weakness: CWE-327
Affected product: Juniper Junos Space
Published: 2026-01-15
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-21907?: 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.
How severe is CVE-2026-21907?: CVE-2026-21907 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-21907 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (8th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21907?: CVE-2026-21907 primarily affects Juniper Junos Space. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-21907?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21907 have an EU (EUVD) identifier?: Yes. CVE-2026-21907 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2700.
When was CVE-2026-21907 published?: CVE-2026-21907 was published on 2026-01-15 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:a:juniper:junos_space:*:*:*:*:*:*:*:*
cpe:2.3:a:juniper:junos_space:24.1:r1:*:*:*:*:*:*
cpe:2.3:a:juniper:junos_space:24.1:r2:*:*:*:*:*:*
cpe:2.3:a:juniper:junos_space:24.1:r3:*:*:*:*:*:*
cpe:2.3:a:juniper:junos_space:24.1:r4:*:*:*:*:*:*

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