CVE-2026-77117: The GNU C Library glibc · Infinite Loop
Affects The GNU C Library glibcSource CVE Database V5
Mentioned vulnerabilities
Not known to be exploited · CVSS 5.9 Medium.
Data as of 26 Oct 2026, 12:30 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 29% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-09-15.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 15 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| The GNU C Libraryglibc | Affected
| Fixed in– |
AI-suggested
Until a fix is available, avoid processing untrusted SHIFT_JISX0213 input with glibc versions 2.3 through 2.44 or ensure output buffers are sufficiently large to prevent splitting code points during conversion.
Description
CVE-2026-77117 is a vulnerability in the GNU C Library (glibc) versions 2.3 through 2.44 involving an infinite loop during conversion of crafted SHIFT_JISX0213 input to UCS-4 or the internal wide character encoding. The issue arises when a SHIFT_JISX0213 sequence decodes to two code points but the output buffer only has room for the first, causing the converter to repeatedly emit a pending character without consuming further input, leading to application hang. This affects only the SHIFT_JISX0213 character set, which is uncommon.