CVE-2018-20796

Publication date 26 February 2019

Last updated 25 August 2025

Ubuntu priority

Cvss 3 Severity Score

Description

In the GNU C Library (aka glibc or libc6) through 2.29, check_dst_limits_calc_pos_1 in posix/regexec.c has Uncontrolled Recursion, as demonstrated by '(\227|)(\\1\\1|t1|\\\2537)+' in grep.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
eglibc	20.04 LTS focal	Not in release
	19.10 eoan	Not in release
	19.04 disco	Not in release
	18.10 cosmic	Not in release
	18.04 LTS bionic	Not in release
	16.04 LTS xenial	Not in release
	14.04 LTS trusty	Ignored end of standard support
glibc	20.04 LTS focal	Ignored
	19.10 eoan	Ignored
	19.04 disco	Ignored end of life
	18.10 cosmic	Ignored end of life
	18.04 LTS bionic	Ignored
	16.04 LTS xenial	Ignored
	14.04 LTS trusty	Not in release

Notes

mdeslaur

glibc regex compiler is not supposed to be exposed to untrusted content, and upstream does not consider this to be a security issue: https://sourceware.org/glibc/wiki/Security%20Exceptions https://lists.gnu.org/r/bug-gnulib/2018-09/msg00068.html as of 2020-06-04, no fix available from upstream. We will not be fixing this issue in Ubuntu, marking as ignored.

Severity score breakdown

CVSS version: CVSS v3.0

Base score 7.5 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	7.5 · High
Exploitability score	-
Impact score	-

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H