CVE-2026-77117 SHIFT_JISX0213 decoding may hang on crafted input
Crafted SHIFT_JISX0213 input causes glibc iconv to hang indefinitely, leading to denial of service in applications using small output buffers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77117?
CVE-2026-77117 is a medium-severity denial of service vulnerability in The GNU C Library glibc, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Converting crafted SHIFT_JISX0213 input to UCS-4 or the internal wide character encoding, for example with iconv, in the GNU C Library version 2.3 to 2.44 may result in the converter making no progress, causing the calling application to hang.
Some SHIFT_JISX0213 sequences decode to two code points. If the output buffer has room for only the first one, the converter stores the second in the conversion state and returns E2BIG, but it never clears that pending character after emitting it on the next call. The converter then keeps emitting the pending character without consuming further input, so an application that retries the conversion loops forever. The input must be attacker controlled and the application must convert it with an output buffer small enough to split the two code points. Only the SHIFT_JISX0213 character set is affected, which is not commonly used. The related defect in the EUC_JISX0213 converter is tracked separately as CVE-2026-80489.
Weakness: CWE-835
Which versions are affected by CVE-2026-77117?
How do I fix CVE-2026-77117?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-77117 being exploited?
There is no known exploitation of CVE-2026-77117 in the wild and no public exploit code.
Sources
Also known as AZL-100959, BELL-CVE-2026-77117, DEBIAN-CVE-2026-77117, ECHO-52f8-53b9-ae20, GHSA-g8c6-x9r9-wj7f, UBUNTU-CVE-2026-77117.