How severe is CVE-2026-21899?

CVE-2026-21899 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.

Is CVE-2026-21899 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-21899?

CVE-2026-21899 affects Nasa Cryptolib. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-21899?

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

Does CVE-2026-21899 have an EU (EUVD) identifier?

Yes. CVE-2026-21899 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1895.

When was CVE-2026-21899 published?

CVE-2026-21899 was published on 2026-01-10 and last updated on 2026-06-17.

CVE-2026-21899

CVE-2026-21899 is a medium-severity vulnerability in Nasa Cryptolib with a CVSS 3.x base score of 4.7. 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 4.7)
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-1895
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, in base64urlDecode, padding-stripping dereferences input[inputLen - 1] before checking that inputLen > 0 or that input != NULL. For inputLen == 0, this becomes an OOB read at input[-1], potentially crashing the process. If input == NULL and inputLen == 0, it dereferences NULL - 1. This issue has been patched in version 1.4.3.

Frequently asked questions

What is CVE-2026-21899?: 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, in base64urlDecode, padding-stripping dereferences input[inputLen - 1] before checking that inputLen > 0 or that input != NULL. For inputLen == 0, this becomes an OOB read at input[-1], potentially crashing the process. If input == NULL and inputLen == 0, it dereferences NULL - 1. This issue has been patched in version 1.4.3.
How severe is CVE-2026-21899?: CVE-2026-21899 has a CVSS 3.x base score of 4.7, rated medium severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability low.
Is CVE-2026-21899 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-21899?: CVE-2026-21899 affects Nasa Cryptolib. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-21899?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-21899 have an EU (EUVD) identifier?: Yes. CVE-2026-21899 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-1895.
When was CVE-2026-21899 published?: CVE-2026-21899 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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