How severe is CVE-2026-21900?

CVE-2026-21900 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 none, integrity none, and availability high.

Is CVE-2026-21900 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21900?

CVE-2026-21900 affects Nasa Cryptolib. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21900?

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

Does CVE-2026-21900 have an EU (EUVD) identifier?

Yes. CVE-2026-21900 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1894.

When was CVE-2026-21900 published?

CVE-2026-21900 was published on 2026-01-10 and last updated on 2026-06-17.

CVE-2026-21900

CVE-2026-21900 is a medium-severity vulnerability in Nasa Cryptolib 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-125.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v4: 8.2
EPSS exploit prediction: 1% (40th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-1894
Weakness: CWE-125
Affected product: Nasa Cryptolib
Published: 2026-01-10
Last modified: 2026-06-17

Description

CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP) to secure communications between a spacecraft running the core Flight System (cFS) and a ground station. Prior to version 1.4.3, an out-of-bounds heap read vulnerability in cryptography_encrypt() occurs when parsing JSON metadata from KMC server responses. The flawed strtok iteration pattern uses ptr + strlen(ptr) + 1 which reads one byte past allocated buffer boundaries when processing short or malformed metadata strings. This issue has been patched in version 1.4.3.

Frequently asked questions

What is CVE-2026-21900?: CryptoLib provides a software-only solution using the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP) to secure communications between a spacecraft running the core Flight System (cFS) and a ground station. Prior to version 1.4.3, an out-of-bounds heap read vulnerability in cryptography_encrypt() occurs when parsing JSON metadata from KMC server responses. The flawed strtok iteration pattern uses ptr + strlen(ptr) + 1 which reads one byte past allocated buffer boundaries when processing short or malformed metadata strings. This issue has been patched in version 1.4.3.
How severe is CVE-2026-21900?: CVE-2026-21900 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 none, integrity none, and availability high.
Is CVE-2026-21900 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (40th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21900?: CVE-2026-21900 affects Nasa Cryptolib. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21900?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21900 have an EU (EUVD) identifier?: Yes. CVE-2026-21900 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1894.
When was CVE-2026-21900 published?: CVE-2026-21900 was published on 2026-01-10 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nasa:cryptolib:*:*:*:*:*:*:*:*

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