CVE-2021-21353

CRITICALNVD 9.09.0
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This critical-severity CVE scores 9.0 under NVD CVSS v3. EPSS exploit probability: 4.3% (91st percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 6.8 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2021-03-03) is not newer than that change (2026-11-02), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this weekElevated

Also known asEUVD-2021-0685 (ENISA EUVD) · GHSA-p493-635q-r6gr (GitHub Security Advisories)Source: ENISA EUVD

9.0EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • Public exploit or proof-of-concept code is available
CISA-KEV: Not listedEPSS PROB: 4.3%CVSS: 9.0Exploit: Public PoCExposed services: Not assessed

A fix is available — apply it.

Pug is an npm package which is a high-performance template engine. In pug before version 3.0.1, if a remote attacker was able to control the pretty option of the pug compiler, e.g. if you spread a user provided object such as the query parameters of a request into the pug template inputs, it was possible for them to achieve remote code execution on the node.js backend. This is fixed in version 3.0.1. This advisory applies to multiple pug packages including "pug", "pug-code-gen". pug-code-gen has a backported fix at version 2.0.3. This advisory is not exploitable if there is no way for un-trusted input to be passed to pug as the pretty option, e.g. if you compile templates in advance before applying user input to them, you do not need to upgrade.

CVSS v3
9.0
EG Score
9.0CRITICALmedium confidence
EG Risk
57
EG Risk 57/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity90% × 45%
Impact severity (EG Severity): CVSS 9.0 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
4.3%
EPSS %ILE
91st
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is its impact severity (EG Severity), not escalated.

EG Severity
9.0 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
4.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-02). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)14 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

March 3, 2021

Last Modified

November 2, 2026

Advisory Details (5)

Auto-updated Oct 25, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github_pr, github_release, github.
GitHub pull request Patch Available

fix: sanitise and escape the `pretty` option

Patch available: pugjs/pug pug-code-gen@3.0.2 (PR #3314 merged 2021-02-28)

https://github.com/pugjs/pug/pull/3314
Web page🟡 PoC Available

Code injection vulnerability in visitMixin and visitMixinBlock through "pretty" option · Issue #3312 · pugjs/pug · GitHub

https://github.com/pugjs/pug/issues/3312
GitHub commit Patch Available

commit 991e78f7c422 (pugjs/pug)

Patch available: pugjs/pug pug-code-gen@3.0.2 (contains commit 991e78f7c422)

https://github.com/pugjs/pug/commit/991e78f7c4220b2f8da042877c6f0ef5a4683be0
GitHub advisoryMentions a patch (unverified)

Remote code execution via the `pretty` option. · Advisory · pugjs/pug · GitHub

https://github.com/pugjs/pug/security/advisories/GHSA-p493-635q-r6gr
GitHub release Patch Available

pug@3.0.1

Patch available: pugjs/pug pug@3.0.1

https://github.com/pugjs/pug/releases/tag/pug%403.0.1

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
npmpug @ 3.0.1 (fixes < 3.0.1)—ghsa
npmpug-code-gen @ 2.0.3 (fixes < 2.0.3)—ghsa
npmpug-code-gen @ 3.0.2 (fixes >= 3.0.0, < 3.0.2)—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(2 across 1 ecosystem)
npm(2)
PackageVulnerable rangeFix by version rangeDependents
pug—
  • every version up to 3.0.1: fixed in 3.0.1
—
pug-code-gen—
  • every version up to 2.0.3: fixed in 2.0.3
  • 3.0.0 up to 3.0.2: fixed in 3.0.2
—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 41× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 95 of 213 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 5 repeat rows among the latest 100 are merged into the row they repeat. The 118 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 18:28 UTCEG score recompute▲ 2.20
  2. 2026-11-02 18:28 UTCGHSA enrichmentGHSA-p493-635q-r6gr · GitHub severity MODERATE · GitHub CVSS 6.8
  3. 2026-11-02 18:26 UTCNVD updateCVSS v3 → 9 · severity → CRITICAL
  4. 2026-11-02 18:09 UTCEG score recompute
  5. 2026-11-02 18:09 UTCGHSA enrichmentGHSA-p493-635q-r6gr · GitHub severity MODERATE · GitHub CVSS 6.8
  6. 2026-11-01 08:34 UTCGHSA enrichmentGHSA-p493-635q-r6gr · GitHub severity MODERATE · GitHub CVSS 6.8
  7. 2026-11-01 08:34 UTCEG score recompute
  8. 2026-10-31 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  9. 2026-10-30 16:29 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  10. 2026-10-29 16:29 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  11. 2026-10-28 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  12. 2026-10-27 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  13. 2026-10-26 16:27 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  14. 2026-10-25 18:35 UTCEG score recompute
  15. 2026-10-25 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  16. 2026-10-25 00:23 UTCEG score recompute
  17. 2026-10-24 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  18. 2026-10-23 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  19. 2026-10-22 16:29 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  20. 2026-10-21 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  21. 2026-10-20 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  22. 2026-10-19 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  23. 2026-10-19 00:25 UTCOSV refresh
  24. 2026-10-18 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  25. 2026-10-18 09:11 UTCEG score recompute
Show 70 more
  1. 2026-10-17 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  2. 2026-10-16 16:33 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  3. 2026-10-15 16:28 UTCEPSS rescoreEPSS 4.3% · 91st percentile
  4. 2026-10-14 16:28 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  5. 2026-10-13 16:28 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  6. 2026-10-12 19:25 UTCEG score recompute
  7. 2026-10-12 16:29 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  8. 2026-10-11 23:50 UTCEG score recompute
  9. 2026-10-11 13:43 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  10. 2026-10-10 19:56 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  11. 2026-10-09 20:04 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  12. 2026-10-08 16:39 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  13. 2026-10-07 23:44 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  14. 2026-10-06 15:13 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  15. 2026-10-05 17:40 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  16. 2026-10-04 23:18 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  17. 2026-10-03 14:22 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  18. 2026-10-02 16:22 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  19. 2026-10-01 19:46 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  20. 2026-09-30 15:29 UTCEG score recompute
  21. 2026-09-30 15:00 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  22. 2026-09-28 13:47 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  23. 2026-09-27 13:41 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  24. 2026-09-26 15:54 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  25. 2026-09-26 07:55 UTCOSV refresh
  26. 2026-09-26 00:21 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  27. 2026-09-24 14:00 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  28. 2026-09-23 13:44 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  29. 2026-09-22 14:44 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  30. 2026-09-21 20:28 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  31. 2026-09-19 15:37 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  32. 2026-09-18 19:23 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  33. 2026-09-17 19:23 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  34. 2026-09-16 14:04 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  35. 2026-09-15 03:06 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  36. 2026-09-12 14:57 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  37. 2026-09-11 09:33 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  38. 2026-09-10 09:29 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  39. 2026-09-08 21:56 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  40. 2026-09-07 15:58 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  41. 2026-09-06 21:31 UTCOSV refresh
  42. 2026-09-06 13:44 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  43. 2026-09-05 15:25 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  44. 2026-09-04 13:57 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  45. 2026-09-04 05:03 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  46. 2026-09-02 14:08 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  47. 2026-09-01 13:50 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  48. 2026-09-01 03:32 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  49. 2026-08-30 19:14 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  50. 2026-08-30 01:19 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  51. 2026-08-28 21:37 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  52. 2026-08-27 14:22 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  53. 2026-08-26 14:42 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  54. 2026-08-25 13:45 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  55. 2026-08-23 00:16 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  56. 2026-08-21 23:46 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  57. 2026-08-20 22:52 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  58. 2026-08-20 07:25 UTCOSV refresh
  59. 2026-08-19 17:01 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  60. 2026-08-18 13:45 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  61. 2026-08-17 13:43 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  62. 2026-08-16 14:52 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  63. 2026-08-16 02:11 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  64. 2026-08-15 01:27 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  65. 2026-08-13 21:57 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  66. 2026-08-12 13:47 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  67. 2026-08-11 13:38 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  68. 2026-08-09 13:43 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  69. 2026-08-08 16:33 UTCEPSS rescoreEPSS 4.3% · 90th percentile
  70. 2026-08-07 16:23 UTCEPSS rescoreEPSS 4.3% · 90th percentile

Publicly available exploits

(1 reference)

Public exploit code is referenced for this CVE (1 GitHub PoC). Defenders should treat patch urgency accordingly.

  • GitHub PoCjinsu9758/PUG-RCE-CVE-2021-21353-POC
    Published Mar 29, 2025
    Open source ↗

Related CVEs(same product + same CWE)

Same product

1 shown

npm:pug

Frequently asked(5)

What is CVE-2021-21353?
CVE-2021-21353 is a critical-severity vulnerability; its CVE record was published on March 3, 2021. Pug is an npm package which is a high-performance template engine. In pug before version 3.0.1, if a remote attacker was able to control the pretty option of the pug compiler, e.g. if you spread a user provided object such as the query parameters of a request into the pug template inputs, it was…
When was the CVE record for CVE-2021-21353 published?
The CVE record for CVE-2021-21353 was published on March 3, 2021. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of November 2, 2026; the record at its source may have been updated since.
Is CVE-2021-21353 actively exploited?
CVE-2021-21353 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4.3% probability of exploitation in the next 30 days (91st percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-21353?
CVE-2021-21353 has a CVSS v3 base score of 9.0 (NVD).
How do I remediate CVE-2021-21353?
A fix for CVE-2021-21353 is available: update to the fixed version the vendor names in its advisory.

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