CVE detail
CVE-2026-5928
Calling the ungetwc function on a FILE stream with wide characters encoded in a character set that has overlaps between its single byte and multi-byte character encodings, in the GNU C Library version 2.43 or earlier, may result in an attempt to read bytes before an allocated buffer, potentially resulting in unintentional disclosure of neighboring data in the heap, or a program crash. A bug in the wide character pushback implementation (_IO_wdefault_pbackfail in libio/wgenops.c) causes ungetwc() to operate on the regular character buffer (fp->_IO_read_ptr) instead of the actual wide-stream read pointer (fp->_wide_data->_IO_read_ptr). The program crash may happen in cases where fp->_IO_read_ptr is not initialized and hence points to NULL. The buffer under-read requires a special situation where the input character encoding is such that there are overlaps between single byte representations and multibyte representations in that encoding, resulting in spurious matches. The spurious match case is not possible in the standard Unicode character sets.
Buzz score
Why this CVE is surfacing
This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.
Buzz score components · mention 13.9 · diversity 15.0 · KEV 0.0 · OTX 0.0 · PoC 0.0
Why it matters now
Mention timeline
- Total mentions
- 0
- within the 30d window
- Peak daily
- 0
- highest bucket
Evidence
Source links by recency
3 source links · newest first
Information published.
vendormsrc.microsoft.comJun 3, 2026, 8:40 AM- https://cert-portal.siemens.com/productcert/html/ssa-082556.htmlcert-portal.siemens.com
No excerpt available.
Vendor Advisorycert-portal.siemens.comApr 20, 2026, 9:16 PM - https://sourceware.org/bugzilla/show_bug.cgi?id=33998sourceware.org
No excerpt available.
Exploitsourceware.orgApr 20, 2026, 9:16 PM
Exploit code
Public exploit repository references
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0 repository references · best confidence N/A · max 0 stars
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