CVE-2026-21899 CryptoLib has an out-of-bounds read and crash vulnerability when decoding an empty Base64url string
An attacker can cause a denial of service by sending an empty Base64url string, triggering a null pointer dereference or out-of-bounds read in CryptoLib.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-21899?
CVE-2026-21899 is a medium-severity vulnerability in nasa CryptoLib, published on 10 Jan 2026. An attacker needs administrator access to exploit it, 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, 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.
Weakness: CWE-125
Which versions are affected by CVE-2026-21899?
It affects 1 product.
Products include Nasa Cryptolib.
How do I fix CVE-2026-21899?
No fix has been published for CVE-2026-21899 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-21899 being exploited?
There is no known exploitation of CVE-2026-21899 in the wild and no public exploit code.
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-wc29-5hw7-mpj8.