CVE-2020-28493 | Regular Expression Denial of Service (ReDoS)

Exp

This affects the package jinja2 from 0.0.0 and before 2.11.3. The ReDoS vulnerability is mainly due to the `_punctuation_re regex` operator and its use of multiple wildcards. The last wildcard is the most exploitable as it searches for trailing punctuation. This issue can be mitigated by Markdown to format user content instead of the urlize filter, or by implementing request timeouts and limiting process memory.

Published: 2021-02-01 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2020-28493 is rated High Exploit Risk (66.9/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 3.55%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2020-28493

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2020-28493

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-19 3.57% 3.55% -0.03%
2 2026-06-15 0.21% 3.57% +3.37%
3 2025-11-21 — 0.21% —

Full EPSS history (13 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2020-28493

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:L)
Might cause slowdowns, glitches, or partial disruption—not a full brick.
 3.9 1.4 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2020-28493

GitHub Security Advisory for CVE-2020-28493

GHSA-g3rq-g295-4j3m · Severity: medium · Ecosystem: pip — Regular Expression Denial of Service (ReDoS) in Jinja2

OS Trackers for CVE-2020-28493

vendor priority summary link
alpine medium CVE-2020-28493: 1 source package rows (py3-jinja2); 7 state rows across 7 repos (3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 7, open 0. https://security.alpinelinux.org/vuln/CVE-2020-28493
debian not yet assigned CVE-2020-28493 not yet assigned priority: Debian including 1 source packages (jinja2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2020-28493
gentoo low CVE-2020-28493: 1 GLSA(s) (202107-19), 1 atom(s) (dev-python/jinja); latest impact low. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-28493
redhat medium — https://access.redhat.com/security/cve/CVE-2020-28493
suse high CVE-2020-28493 severity important: SUSE including 322 source package names (1.5.7.4.1.1512:python3-Jinja2-2.10.1-3.10.2, 1.8.6.0.3.2.5:python3-Jinja2-2.10.1-3.10.2, …), 641 product×package rows across 308 product lines (Container ses/7.1/cephcsi/cephcsi, Container ses/7.1/rook/ceph, … (308 product lines)): Fixed 475, Known Affected 166. https://www.suse.com/security/cve/CVE-2020-28493/
ubuntu low CVE-2020-28493 low priority: Ubuntu including 1 source packages (jinja2), 12 status rows across 12 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, trusty, upstream, xenial): released 5, not-affected 4, ignored 3. https://ubuntu.com/security/CVE-2020-28493

Affected software / configurations for CVE-2020-28493

Vendor Product Version Raw CPE
palletsprojects jinja < 2.11.3 cpe:2.3:a:palletsprojects:jinja:*:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*

References for CVE-2020-28493

cvelogic Threat Intelligence