CVE-2026-5928Public exploitNetwork attack vector

Heap disclosure or crash via wrong stream pointer

Published Apr 20, 2026 · Updated Apr 20, 2026

Buffer under-read in GNU Project glibc 2.1.1-89 through 2.43 allows remote attackers to disclose heap data or crash a process via ungetwc. _IO_wdefault_pbackfail in libio/wgenops.c compares and decrements fp->_IO_read_ptr, the byte-stream pointer, instead of fp->_wide_data->_IO_read_ptr for the wide stream. Reachability requires a character encoding whose single-byte and multibyte forms overlap; standard Unicode encodings cannot trigger the spurious match.

CVSS severity7.5
High
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer under-read in GNU Project glibc 2.1.1-89 through 2.43 allows remote attackers to disclose heap data or crash a process via ungetwc. _IO_wdefault_pbackfail in libio/wgenops.c compares and decrements fp->_IO_read_ptr, the byte-stream pointer, instead of fp->_wide_data->_IO_read_ptr for the wide stream. Reachability requires a character encoding whose single-byte and multibyte forms overlap; standard Unicode encodings cannot trigger the spurious match.

The record

CVE
CVE-2026-5928
Published
Apr 20, 2026
Updated
Apr 20, 2026
Vendor
The GnuPG Project
Product
glibc
Classifications
CWE-127, CAPEC-540, CAPEC-267
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.1.1-89 <=2.43

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The GnuPG Project · glibcversion=2.1.1-89 <=2.43

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-127Buffer Under-read
CAPEC-540Overread Buffers
CAPEC-267Leverage Alternate Encoding

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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