CVE-2026-22027: CryptoLib Buffer Overflow Vulnerability

CVE-2026-22027 Overview

CVE-2026-22027 is a heap-based buffer overflow vulnerability in NASA's CryptoLib, a software-only cryptographic solution implementing the CCSDS Space Data Link Security Protocol - Extended Procedures (SDLS-EP). This protocol secures communications between spacecraft running the core Flight System (cFS) and ground stations. The vulnerability exists in the convert_hexstring_to_byte_array() function within the MariaDB Security Association (SA) interface, where decoded bytes are written into a caller-provided buffer without any capacity validation.

Critical Impact

When importing SA fields from the database (e.g., IV, ARSN, ABM), a malformed or oversized hex string in the database can overflow the destination buffer, corrupting adjacent heap memory and potentially enabling code execution or denial of service in spacecraft communication systems.

Affected Products

• NASA CryptoLib versions prior to 1.4.3
• Systems using CryptoLib MariaDB SA interface
• Spacecraft and ground station communication systems implementing SDLS-EP with CryptoLib

Discovery Timeline

• January 10, 2026 - CVE-2026-22027 published to NVD
• January 13, 2026 - Last updated in NVD database

Technical Details for CVE-2026-22027

Vulnerability Analysis

This vulnerability is classified as CWE-122: Heap-based Buffer Overflow. The flaw resides in the convert_hexstring_to_byte_array() function which is responsible for converting hexadecimal string representations from the MariaDB database into byte arrays for cryptographic operations. The function fails to verify that the destination buffer has sufficient capacity to hold the decoded byte data before performing the write operation.

When Security Association fields such as Initialization Vectors (IV), Anti-Replay Sequence Numbers (ARSN), or Authentication Bit Masks (ABM) are imported from the database, an attacker who can manipulate database contents could insert malformed or oversized hex strings. These malicious strings would then overflow the fixed-size destination buffers, corrupting adjacent heap memory structures.

Root Cause

The root cause is the absence of bounds checking in the convert_hexstring_to_byte_array() function. The function accepts a hex string of arbitrary length from the database and writes decoded bytes directly into a caller-provided buffer without validating whether the buffer can accommodate the resulting byte array. This is a classic case of trusting external input without proper validation, particularly dangerous when the input source is a database that could potentially be compromised or contain malformed data.

Attack Vector

The attack requires local access with high privileges, as the attacker must be able to modify the MariaDB database contents that CryptoLib reads from. The exploitation scenario involves:

1. An attacker with database access inserts an oversized or malformed hex string into SA-related fields (IV, ARSN, or ABM columns)
2. When CryptoLib's MariaDB SA interface retrieves these fields, it calls convert_hexstring_to_byte_array()
3. The function decodes the malicious hex string without checking buffer boundaries
4. The decoded bytes overflow the destination buffer, corrupting adjacent heap memory
5. Depending on heap layout, this could lead to denial of service through memory corruption or potentially arbitrary code execution if heap metadata or function pointers are overwritten

The vulnerability mechanism involves the database interface retrieving hex-encoded cryptographic parameters and converting them to binary form. Without length validation, an attacker-controlled hex string exceeding the expected parameter size will overflow the destination buffer. For detailed technical information and the specific code changes, see the GitHub Security Advisory GHSA-3m35-m689-h29x.

Detection Methods for CVE-2026-22027

Indicators of Compromise

• Unexpected crashes or segmentation faults in CryptoLib-dependent applications during database operations
• Abnormally long hex strings in MariaDB SA-related tables (IV, ARSN, ABM fields)
• Memory corruption errors or heap integrity violations in spacecraft communication software
• Unusual database modification patterns targeting Security Association configuration tables

Detection Strategies

• Monitor CryptoLib application logs for memory allocation failures or heap corruption indicators
• Implement database integrity checks to validate hex string lengths in SA configuration tables match expected cryptographic parameter sizes
• Deploy memory protection tools (AddressSanitizer, Valgrind) in development and testing environments to detect heap overflows
• Audit database access logs for unauthorized modifications to Security Association tables

Monitoring Recommendations

• Establish baseline lengths for IV, ARSN, and ABM fields and alert on deviations
• Implement runtime memory monitoring for CryptoLib processes in ground station systems
• Configure database auditing to track all modifications to cryptographic configuration tables
• Monitor system stability metrics for spacecraft communication components using CryptoLib

How to Mitigate CVE-2026-22027

Immediate Actions Required

• Upgrade NASA CryptoLib to version 1.4.3 or later immediately
• Audit MariaDB databases used with CryptoLib for any oversized or malformed hex strings in SA fields
• Restrict database access permissions to minimize the attack surface
• Implement input validation at the database layer to enforce maximum field lengths

Patch Information

The vulnerability has been patched in CryptoLib version 1.4.3. The fix implements proper bounds checking in the convert_hexstring_to_byte_array() function to ensure hex strings from the database do not exceed the destination buffer capacity. Organizations should update to this version immediately.

• GitHub Release v1.4.3
• GitHub Commit with Fix

Workarounds

• Implement database-level constraints to limit the maximum length of hex string fields used by CryptoLib SA interface
• Add application-layer validation to verify hex string lengths before passing to CryptoLib functions
• Deploy database access controls to restrict write access to SA configuration tables to authorized systems only
• Consider isolating CryptoLib database operations in sandboxed environments until patching is complete

# Configuration example - Database field length constraints for MariaDB
# Add column length constraints to prevent oversized hex strings
ALTER TABLE security_associations 
  MODIFY iv VARCHAR(64) NOT NULL,
  MODIFY arsn VARCHAR(32) NOT NULL,
  MODIFY abm VARCHAR(128) NOT NULL;

# Verify CryptoLib version after upgrade
cryptolib --version
# Expected output: CryptoLib v1.4.3 or higher