CVE-2026-55969 Overview
CVE-2026-55969 is an integer overflow vulnerability [CWE-190] affecting multiple Apache Thrift language bindings, including C++, c_glib, Go, netstd, Delphi, and Haxe. The flaw exists in all Apache Thrift versions prior to 0.24.0. An unauthenticated remote attacker can trigger the overflow by sending crafted network input to a service built with an affected binding. Successful exploitation degrades service availability without requiring authentication or user interaction. The Apache Thrift project has published a fix in version 0.24.0.
Critical Impact
Remote, unauthenticated attackers can crash or destabilize Apache Thrift services across six language bindings by triggering an integer overflow during message processing.
Affected Products
- Apache Thrift C++ bindings before 0.24.0
- Apache Thrift c_glib, Go, and netstd bindings before 0.24.0
- Apache Thrift Delphi and Haxe bindings before 0.24.0
Discovery Timeline
- 2026-07-27 - CVE-2026-55969 published to NVD
- 2026-07-27 - Last updated in NVD database
Technical Details for CVE-2026-55969
Vulnerability Analysis
CVE-2026-55969 is an integer overflow or wraparound weakness in six Apache Thrift language bindings. Thrift is a cross-language RPC framework that serializes structured data over the network. During deserialization, the affected bindings perform arithmetic on length or size fields drawn from attacker-controlled input. When those values approach the maximum of the underlying integer type, the arithmetic wraps around to a small or negative value. Downstream allocation, iteration, or bounds-checking logic then operates on the wrapped value, producing corrupted state or a process crash. The vector is network-reachable, requires no privileges, and needs no user interaction.
Root Cause
The root cause is unchecked arithmetic on size fields carried in the Thrift binary and compact protocols. Fields such as list, set, map, and string lengths are read directly from the wire and multiplied or added to internal offsets before validation against the actual buffer size. On overflow, the sanity checks that would normally reject oversized payloads are bypassed, because the wrapped result appears legitimate. The defect spans six independent binding implementations because each replicated the same unsafe pattern.
Attack Vector
An attacker sends a single crafted Thrift message to any service that accepts input through one of the affected bindings. The message declares a container or string length chosen to overflow the size computation. Once the wrapped value is used for allocation or copying, the service enters an inconsistent state and terminates. Because the CVSS 4.0 vector reports availability impact only, exploitation is expected to disrupt service continuity rather than leak data or execute code. See the Apache Mailing List Thread for the vendor advisory and the Openwall OSS Security Update for coordinated disclosure details.
Detection Methods for CVE-2026-55969
Indicators of Compromise
- Unexpected termination or restart of Thrift-based RPC services correlated with inbound traffic bursts.
- Thrift server logs recording deserialization exceptions, allocation failures, or negative-length errors.
- Inbound TCP flows to Thrift listener ports carrying container or string length fields near INT32_MAX.
Detection Strategies
- Inspect Thrift traffic at the application layer for declared list, set, map, or string lengths that exceed the payload size.
- Track process crash telemetry for services linked against Apache Thrift bindings older than 0.24.0.
- Correlate anomalous connection resets on Thrift ports with concurrent CPU or memory spikes on the host.
Monitoring Recommendations
- Enable core-dump collection and crash reporting on hosts running Thrift services during the patch window.
- Alert on repeated malformed Thrift frames from a single source address within short time intervals.
- Baseline normal message sizes for each Thrift endpoint and flag statistical outliers.
How to Mitigate CVE-2026-55969
Immediate Actions Required
- Inventory every service that links against Apache Thrift C++, c_glib, Go, netstd, Delphi, or Haxe bindings.
- Upgrade all identified components to Apache Thrift 0.24.0 and rebuild dependent applications.
- Restrict network exposure of Thrift listeners to trusted client networks until patching is complete.
Patch Information
Apache Thrift 0.24.0 contains the fix. Users of any affected binding must upgrade to this version and redeploy all binaries that statically or dynamically link the Thrift runtime. Refer to the Apache Mailing List Thread for the official upgrade announcement.
Workarounds
- Place a reverse proxy or firewall in front of Thrift services to enforce a maximum request size below the overflow threshold.
- Terminate Thrift traffic through a mutually authenticated TLS tunnel to prevent unauthenticated remote access.
- Where feasible, switch consumers to a Thrift binding not listed as affected until the upgrade completes.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
