CVE-2026-21900 CryptoLib Has Out-of-Bounds Read in KMC Encrypt Metadata Parsing via Flawed strtok Pattern
An out-of-bounds heap read in CryptoLib allows attackers to disclose memory or cause denial of service via malformed KMC metadata.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-21900?
CVE-2026-21900 is a high-severity memory corruption vulnerability in nasa CryptoLib, published on 10 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-125
Which versions are affected by CVE-2026-21900?
It affects 1 product.
Products include Nasa Cryptolib.
How do I fix CVE-2026-21900?
No fix has been published for CVE-2026-21900 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-21900 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-21900 exists.
Other vulnerabilities in nasa CryptoLib
- CVE-2025-30216 CryptoLib Has Heap Overflow in Crypto_TM_ProcessSecurity due to Unchecked Secondary Header Length
- CVE-2025-30356 Heap Buffer Overflow via Incomplete Length Check in `Crypto_TC_ApplySecurity`
- CVE-2025-29909 CryptoLib's Crypto_TC_ApplySecurity() Has a Heap Buffer Overflow Vulnerability
- CVE-2025-29911 CryptoLib Has Heap Buffer Overflow in Crypto_AOS_ProcessSecurity Function
- CVE-2025-29912 CryptoLib Has Heap Buffer Overflow Due to Unsigned Integer Underflow in Crypto_TC_ProcessSecurity
Sources
Also known as GHSA-4g6v-36fv-qcvw.