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NVD / CVE Program· CNA GitHub_M

CVE-2026-21900: CryptoLib Has Out-of-Bounds Read in KMC Encrypt Metadata Parsing via Flawed strtok Pattern

Noroxi assessment

Priority: Monitor (action score 32/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.59% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: nasa CryptoLib 1.4.3.

Low priority for now. Upgrade to nasa CryptoLib 1.4.3 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 8.2 · v4.0—No exploit Fix available
Published
Jan 9, 2026
Updated
Jun 17, 2026
EPSS
0.5% · 48th percentile

Report tools

JSON

Action score

32

Monitor

Low priority for now.

CVSS
32 / 40 · 8.2 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.5%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
8.2
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-21900

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
nasacryptolib

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • nasa cryptolibbefore 1.4.3

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • nasa CryptoLib

    • < 1.4.3affected

Same product

nasa: all records

Other highest-scoring records for the same primary product.

  • CVE-2025-46674NASA CryptoLib before 1.3.2 uses Extended Procedures that are a Work in Progress (not intended for use during flight), potentially leading t
    39Monitor
  • CVE-2025-46673NASA CryptoLib before 1.3.2 does not check whether the SA is in an operational state before use, possibly leading to a bypass of the Space D
    39Monitor
  • CVE-2025-30356Heap Buffer Overflow via Incomplete Length Check in `Crypto_TC_ApplySecurity`
    37Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-21898Jan 9, 2026 · CryptoLib Has Out-of-bounds Read in Crypto_AOS_ProcessSecurity
    32Monitor
  • ← EarlierCVE-2026-21899Jan 9, 2026 · CryptoLib has an out-of-bounds read and crash vulnerability when decoding an empty Base64url string
    19Monitor
  • Later →CVE-2026-22023Jan 9, 2026 · CryptoLib Has Out-of-Bounds Read in KMC AEAD Encrypt Metadata Parsing via Flawed strtok Pattern
    32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
nasa CryptoLib1.4.3 · descriptionVendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2025-29913298 days apartCryptoLib's Crypto_TC_Prep_AAD Has Buffer Overflow Due to Integer Underflow
    35Monitor
  • CVE-2026-218980 days apartCryptoLib Has Out-of-bounds Read in Crypto_AOS_ProcessSecurity
    32Monitor
  • CVE-2026-220230 days apartCryptoLib Has Out-of-Bounds Read in KMC AEAD Encrypt Metadata Parsing via Flawed strtok Pattern
    32Monitor
  • CVE-2024-44910469 days apartNASA CryptoLib v1.3.0 was discovered to contain an Out-of-Bounds read via the AOS subsystem (crypto_aos.c).
    30Monitor
  • CVE-2024-44911469 days apartNASA CryptoLib v1.3.0 was discovered to contain an Out-of-Bounds read via the TC subsystem (crypto_tc.c).
    30Monitor
  • CVE-2024-44912469 days apartNASA CryptoLib v1.3.0 was discovered to contain an Out-of-Bounds read via the TM subsystem (crypto_tm.c).
    30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-125 · Out-of-bounds Read

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records