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CVE Vulnerabilities

CVE-2021-27291

Inefficient Regular Expression Complexity

Published: Mar 17, 2021 | Modified: Nov 21, 2024
CVSS 3.x
7.5
HIGH
Source:
NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 2.x
5 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P
RedHat/V2
RedHat/V3
7.5 MODERATE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2021-27291
CWEhttps://cwe.mitre.org/data/definitions/1333.html

In pygments 1.1+, fixed in 2.7.4, the lexers used to parse programming languages rely heavily on regular expressions. Some of the regular expressions have exponential or cubic worst-case complexity and are vulnerable to ReDoS. By crafting malicious input, an attacker can cause a denial of service.

Weakness

The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.

Affected Software

NameVendorStart VersionEnd Version
PygmentsPygments1.1 (including)2.7.4 (excluding)
Red Hat Automation Hub 4.2 for RHEL 7RedHatautomation-hub-0:4.2.2-1.el7pc*
Red Hat Automation Hub 4.2 for RHEL 7RedHatpython3-django-0:2.2.18-1.el7pc*
Red Hat Automation Hub 4.2 for RHEL 7RedHatpython-bleach-0:3.3.0-1.el7pc*
Red Hat Automation Hub 4.2 for RHEL 7RedHatpython-bleach-allowlist-0:1.0.3-1.el7pc*
Red Hat Automation Hub 4.2 for RHEL 7RedHatpython-galaxy-importer-0:0.2.15-1.el7pc*
Red Hat Automation Hub 4.2 for RHEL 7RedHatpython-galaxy-ng-0:4.2.2-1.el7pc*
Red Hat Automation Hub 4.2 for RHEL 7RedHatpython-pulp-ansible-1:0.5.6-1.el7pc*
Red Hat Automation Hub 4.2 for RHEL 8RedHatautomation-hub-0:4.2.2-1.el8pc*
Red Hat Automation Hub 4.2 for RHEL 8RedHatpython3-django-0:2.2.18-1.el8pc*
Red Hat Automation Hub 4.2 for RHEL 8RedHatpython-bleach-0:3.3.0-1.el8pc*
Red Hat Automation Hub 4.2 for RHEL 8RedHatpython-bleach-allowlist-0:1.0.3-1.el8pc*
Red Hat Automation Hub 4.2 for RHEL 8RedHatpython-galaxy-importer-0:0.2.15-1.el8pc*
Red Hat Automation Hub 4.2 for RHEL 8RedHatpython-galaxy-ng-0:4.2.2-1.el8pc*
Red Hat Automation Hub 4.2 for RHEL 8RedHatpython-pulp-ansible-1:0.5.6-1.el8pc*
Red Hat Enterprise Linux 8RedHatpython36:3.6-8050020210811103506.982725ab*
Red Hat Enterprise Linux 8RedHatpython27:2.7-8050020210811095446.3e7ace8b*
Red Hat Enterprise Linux 8RedHatresource-agents-0:4.1.1-98.el8*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatpython27-babel-0:0.9.6-10.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatpython27-python-0:2.7.18-3.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatpython27-python-jinja2-0:2.6-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7RedHatpython27-python-pygments-0:1.5-5.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSRedHatpython27-babel-0:0.9.6-10.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSRedHatpython27-python-0:2.7.18-3.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSRedHatpython27-python-jinja2-0:2.6-16.el7*
Red Hat Software Collections for Red Hat Enterprise Linux 7.7 EUSRedHatpython27-python-pygments-0:1.5-5.el7*
EricUbuntubionic*
EricUbuntudevel*
EricUbuntuesm-apps/jammy*
EricUbuntuesm-apps/noble*
EricUbuntufocal*
EricUbuntugroovy*
EricUbuntuhirsute*
EricUbuntuimpish*
EricUbuntujammy*
EricUbuntukinetic*
EricUbuntulunar*
EricUbuntumantic*
EricUbuntunoble*
EricUbuntuoracular*
EricUbuntuplucky*
EricUbuntuquesting*
EricUbuntutrusty*
EricUbuntuxenial*
PygmentsUbuntubionic*
PygmentsUbuntudevel*
PygmentsUbuntuesm-infra-legacy/trusty*
PygmentsUbuntuesm-infra/bionic*
PygmentsUbuntuesm-infra/focal*
PygmentsUbuntuesm-infra/xenial*
PygmentsUbuntufocal*
PygmentsUbuntugroovy*
PygmentsUbuntuhirsute*
PygmentsUbuntuimpish*
PygmentsUbuntujammy*
PygmentsUbuntukinetic*
PygmentsUbuntulunar*
PygmentsUbuntumantic*
PygmentsUbuntunoble*
PygmentsUbuntuoracular*
PygmentsUbuntuplucky*
PygmentsUbuntuprecise/esm*
PygmentsUbuntuquesting*
PygmentsUbuntutrusty*
PygmentsUbuntutrusty/esm*
PygmentsUbuntuupstream*
PygmentsUbuntuxenial*

Extended Description

	  Attackers can create crafted inputs that
	  intentionally cause the regular expression to use
	  excessive backtracking in a way that causes the CPU
	  consumption to spike.

Potential Mitigations

References

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