CVE-2026-62353 Overview
CVE-2026-62353 is an out-of-bounds read vulnerability [CWE-125] in TDengine, an open-source time-series database used in Internet of Things (IoT) deployments. The flaw resides in the tGetToken() function within source/libs/parser/src/parTokenizer.c. When the tokenizer processes a SQL string literal ending with a trailing backslash such as 'abc\, it advances past the backslash and reads one byte beyond the null terminator. An authenticated user with permission to submit SQL queries can trigger the flaw to crash the server and potentially leak adjacent process memory. Versions prior to 3.4.1.14 are affected, and the issue is fixed in 3.4.1.14.
Critical Impact
Authenticated attackers can crash the TDengine server and potentially disclose adjacent memory contents through a malformed SQL string literal.
Affected Products
- TDengine versions prior to 3.4.1.14
- source/libs/parser/src/parTokenizer.c SQL parser component
- TDengine deployments accepting authenticated SQL queries
Discovery Timeline
- 2026-07-15 - CVE-2026-62353 published to NVD
- 2026-07-15 - Last updated in NVD database
Technical Details for CVE-2026-62353
Vulnerability Analysis
The vulnerability is a one-byte out-of-bounds read in the TDengine SQL tokenizer. The tGetToken() function parses SQL string literals delimited by single quotes and supports backslash escape sequences. When a literal terminates with an unescaped trailing backslash immediately before the null terminator, the tokenizer treats the backslash as the start of an escape sequence and advances the read cursor one position further. This causes the parser to read a byte from memory located after the string buffer.
Exploitation requires authenticated access to submit SQL queries against the database. Successful triggering results in one of two outcomes. The server process may crash if the adjacent memory falls on an unmapped page, producing a denial-of-service condition. Alternatively, the byte read from adjacent memory may influence subsequent parsing logic in a way that discloses fragments of process memory to the querying client.
Root Cause
The root cause is missing bounds validation in tGetToken() when handling escape sequences at the end of a SQL string literal. The tokenizer does not verify that a character following a backslash lies within the input buffer before dereferencing it. Any trailing-backslash edge case bypasses the string terminator check.
Attack Vector
The attack vector is network-based and requires low-privilege authentication. An attacker submits a crafted SQL statement containing a string literal that ends with a single trailing backslash, for example SELECT * FROM t WHERE name = 'abc\. The malformed literal is passed to the tokenizer, which reads past the buffer boundary. Repeated queries can be used to probe memory or induce process termination.
See the TDengine GitHub Security Advisory GHSA-5r9p-3j4f-gmgp for technical details.
Detection Methods for CVE-2026-62353
Indicators of Compromise
- SQL query logs containing string literals that terminate with an unescaped backslash character before a closing quote or end-of-statement.
- Unexpected taosd server process crashes or restarts correlated with client SQL activity.
- Repeated malformed query submissions from a single authenticated client session.
Detection Strategies
- Enable TDengine query logging and inspect audit logs for SQL statements matching the pattern of a trailing backslash inside a single-quoted literal.
- Monitor the taosd process for abnormal termination signals or segmentation faults recorded in system logs and crash dumps.
- Correlate authentication logs with query submission timestamps to identify low-privilege accounts issuing malformed SQL.
Monitoring Recommendations
- Alert on TDengine server restarts outside of scheduled maintenance windows.
- Track query error rates per user account and flag accounts generating parser errors at elevated frequencies.
- Forward TDengine logs and host telemetry to a centralized SIEM or data lake for cross-source correlation of parser errors with memory-related crash events.
How to Mitigate CVE-2026-62353
Immediate Actions Required
- Upgrade all TDengine instances to version 3.4.1.14 or later, which contains the fix for tGetToken().
- Audit database user accounts and remove SQL query privileges from accounts that do not require them.
- Restrict network access to the TDengine service so only trusted application hosts can reach the SQL interface.
Patch Information
The vulnerability is fixed in TDengine version 3.4.1.14. The upstream fix modifies the tokenizer in source/libs/parser/src/parTokenizer.c to correctly handle trailing backslashes without reading past the null terminator. Refer to the TDengine GitHub Security Advisory GHSA-5r9p-3j4f-gmgp for release details.
Workarounds
- Place TDengine behind a query proxy or application layer that validates and rejects SQL string literals ending in an unescaped backslash before forwarding them to the server.
- Limit which authenticated roles can execute ad-hoc SQL, restricting query submission to service accounts used by vetted applications.
- Deploy network segmentation and firewall rules to prevent untrusted clients from reaching the TDengine SQL port until patching is complete.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
