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Fencer Vulns
critical 9.1

CVE-2018-17983 json

Mercurial Out-of-bounds Read vulnerability

published 2018-10-04 8 y ago modified 2026-06-17 4 mo ago also GHSA-p575-cf9h-wv42 , PYSEC-2018-91 , EUVD-2018-0098

cvss
9.1
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.0%
EPSS 2.0% chance of exploitation in 30 days, percentile 80%
public exploits
0
none known

Summary

cext/manifest.c in Mercurial before 4.7.2 has an out-of-bounds read during parsing of a malformed manifest entry.

Patch / fix

  • pypi mercurial 4.7.2
  • mercurial mercurial 4.7.2
  • mercurial Debian 14, Debian 13, Debian 12 4.7.2-1

debian advisories DEBIAN-CVE-2018-17983

  • mercurial Ubuntu 18.04 LTS 4.5.3-1ubuntu2.2

ubuntu advisories UBUNTU-CVE-2018-17983

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • mercurial SLE Module for Development Tools 15 4.5.2-3.6.1

suse advisories SUSE-SU-2018:3430-1

  • mercurial openSUSE Tumbleweed 5.9.1-2.1

opensuse advisories openSUSE-SU-2024:10586-1

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-2018-17983 updated cvss 4.3

mercurial: Out-of-bounds read in cext/manifest.c

  • Red Hat Enterprise Linux 6 mercurial, mercurial-hgk, emacs-mercurial, emacs-mercurial-el Red Hat Enterprise Linux 7 mercurial, mercurial-hgk, emacs-mercurial, emacs-mercurial-el Red Hat Enterprise Linux 8 mercurial, mercurial-chg, mercurial-hgk
    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

2.01% chance of exploitation in the next 30 days, higher than 80% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.0 9.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:N/A:P
GitHub 3.0 9.1 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Affected packages

ecosystem package affected fixed in
pypi mercurial
<4.7.2
4.7.2

Classification

Weakness

References

Sources

Fencer Vulns 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.