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Fencer Intel
critical 9.8

CVE-2018-6551 json

The malloc implementation in the GNU C Library (aka glibc or libc6), from version 2.24 to 2.26 on powerpc, and only in version 2.26 on i386…

published 2018-02-02 8 y ago modified 2026-06-17 4 mo ago also EUVD-2018-18303

cvss
9.8
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.2%
EPSS 2.2% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

The malloc implementation in the GNU C Library (aka glibc or libc6), from version 2.24 to 2.26 on powerpc, and only in version 2.26 on i386, did not properly handle malloc calls with arguments close to SIZE_MAX and could return a pointer to a heap region that is smaller than requested, eventually leading to heap corruption.

Patch / fix

  • glibc Debian 14, Debian 13, Debian 12 2.27-1

debian advisories DEBIAN-CVE-2018-6551

  • glibc SLES for SAP 11 SP4, SLES 11 SP4, SLES 11 SP3-TERADATA +3 more 2.11.3-17.110.6.2
  • glibc SLES for SAP 12 SP3, SLES for SAP 12 SP2, SLES for Raspberry Pi 12 SP2 +6 more 2.22-62.6.2

suse advisories SUSE-SU-2018:0565-1SUSE-SU-2018:0451-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-6551 updated cvss 5.3

glibc: integer overflow in malloc functions

  • Red Hat Enterprise Linux 5 glibc, compat-glibc Red Hat Enterprise Linux 6 nscd, glibc, glibc-utils, compat-glibc, glibc-common Red Hat Enterprise Linux 7 nscd, glibc, glibc-utils, compat-glibc, glibc-common Red Hat Enterprise Linux 8 nscd, glibc, libnsl, nss_db, nss_hesiod, glibc-utils, +7 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.21% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 9.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.