Executive brief
The GNU C Library's character encoding converter (iconv) contains a defect in its EUC_JISX0213 decoder that causes it to enter an infinite loop when processing specially crafted input. Applications that use this converter—such as those handling Japanese text encoding—can be made to hang indefinitely if they process attacker-controlled input, resulting in service unavailability.
Technical details
The vulnerability is a denial-of-service (DoS) flaw in the EUC_JISX0213 character set decoder within glibc's iconv implementation. The root cause is that when a multi-codepoint EUC_JISX0213 sequence is split across buffer boundaries, the converter fails to properly clear a pending character stored in the conversion state. On the next call, it re-emits the pending character without consuming input, causing the application to retry the conversion infinitely. The attack requires attacker-controlled input and a small output buffer that splits the two-codepoint sequence. The vulnerability affects glibc versions 2.3 to 2.44; patches have been issued for versions 2.41 through 2.45.
Affected products
- GNU C Library 2.3 to 2.44
Timeline
- 2026-08-26: disclosed
- 2026-08-28: patched: Fix committed to master branch
- 2026-09-15: advisory