Apache Tomcat 10.0.0-M1 to 10.0.6, 9.0.0.M1 to 9.0.46 and 8.5.0 to 8.5.66 did not correctly parse the HTTP transfer-encoding request header in some circumstances leading to the possibility to request smuggling when used with a reverse proxy. Specifically: - Tomcat incorrectly ignored the transfer encoding header if the client declared it would only accept an HTTP/1.0 response; - Tomcat honoured the identify encoding; and - Tomcat did not ensure that, if present, the chunked encoding was the final encoding.
CVE-2021-33037
“▲” beside the score: it is higher than NVD's CVSS score.
Score elevated to 8.3 because EPSS predicted 75% probability of exploitation within the next 30 days (99th percentile of EPSS-scored CVEs) when EchelonGraph scored this CVE. NVD baseline CVSS 5.3 retained for reference. Confidence: see factors.
Also known asEUVD-2021-1563 (ENISA EUVD) · GHSA-4vww-mc66-62m6 (GitHub Security Advisories)Source: ENISA EUVD
- 2,036 internet-facing services (distinct ip:port) on record running an affected version — derived from Shodan data (© Shodan); a patched service can stay counted while its port stays open
- High exploitation likelihood — EPSS 75%
A fix is available — apply it.
2,036 internet-facing services (distinct ip:port) on record running a version that maps to CVE-2021-33037, in our KEV-Exposure radar’s Shodan-derived sample.
How it counts: every 12 hours, when Shodan query credits allow, the radar runs one Shodan query per tracked product, reads up to 100 ip:port services per query, and keeps a service when its banner version matches a CISA-KEV or high-EPSS CVE; a service is dropped when neither a search nor a Shodan InternetDB port re-check has refreshed it for 21 days. A re-check that finds the port still listed by Shodan InternetDB refreshes the service without re-reading the banner, so a patched service can stay counted while its port stays open. A count is a banner-version inference over a sample, not an exploit test and not an internet-wide census, and the unit is a service, not a machine: a machine answering on two ports counts twice.
- CVSS v3
- 5.3
- EG Score
- 8.3HIGHhigh confidence
- EG Risk
- 69EG Risk 69/100
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)Severity53% × 45%Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation75% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability100% × 15%CISA's SSVC Automatable value: yes (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (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 at low or medium mission impact and sooner than that at high. - EPSS PROB
- 75%
- EPSS %ILE
- 99th
- 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 (8.3): severity, escalated by confirmed exploitation. This CVE's 8.3 is EPSS's lift toward 9.0 from its impact severity (EG Severity, CVSS 5.3 MEDIUM): a likelihood of exploitation, not impact.
- EG Severity
- 5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 75% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). 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; Attend at high (mission-essential systems).CISA BOD 26-04: 14 days if the affected system is publicly exposed; 60 days 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; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (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; 60 days if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact partial (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
July 12, 2021
Last Modified
October 8, 2026
Advisory Details (9)
Auto-updated Aug 25, 2026Apache Tomcat: Multiple Vulnerabilities (GLSA 202208-34) — Gentoo security
https://security.gentoo.org/glsa/202208-34[SECURITY] [DLA 2733-1] tomcat8 security update
https://lists.debian.org/debian-lts-announce/2021/08/msg00009.htmlVendor Advisories for CVE-2021-33037(4)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
- RHSA-2022:5532Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat Fuse 7.11.0 release and security update
- RHSA-2022:1179Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat support for Spring Boot 2.5.10 update
- RHSA-2021:4861Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat JBoss Web Server 5.6.0 Security release
- RHSA-2021:4863Red Hat Product SecurityHigh
Red Hat Security Advisory: Red Hat JBoss Web Server 5.6.0 Security release
Patch Availability(6)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| ubuntu | tomcat9-examples (9.0.31-1ubuntu0.2) @ focal | 2026-10-29 | ubuntu |
| redhat | tomcat | 2022-07-07 | redhat |
| redhat | jws5-tomcat-vault-0:1.1.8-4.Final_redhat_00004.1.el8jws | 2021-11-30 | redhat |
| maven | org.apache.tomcat:tomcat @ 10.0.7 (fixes >= 10.0.0-M1, < 10.0.7) | — | ghsa |
| maven | org.apache.tomcat:tomcat @ 9.0.48 (fixes >= 9.0.0-M1, < 9.0.48) | — | ghsa |
| maven | org.apache.tomcat:tomcat @ 8.5.68 (fixes >= 8.5.0, < 8.5.68) | — | 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
(7 across 7 ecosystems)
Debian:10(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| tomcat9 | 9.0.16-4 ... 9.0.31-1~deb10u4 (10 versions) |
| — |
Debian:11(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| tomcat9 | 9.0.43-1 |
| — |
Debian:12(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| tomcat9 | — |
| — |
Debian:13(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| tomcat9 | — |
| — |
Debian:14(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| tomcat9 | — |
| — |
Debian:9(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| tomcat8 | 8.5.14-1 ... 8.5.54-0+deb9u6 (43 versions) |
| — |
Maven(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| org.apache.tomcat:tomcat | 8.5.0 ... 8.5.9 (54 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Additional Vendor Advisories
(1)
Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.
Data Freshness Timeline
(refreshed 8× in last 7d / 29× 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 87 of 149 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. 13 repeat rows among the latest 100 are merged into the row they repeat. The 62 oldest rows on record are not shown and were not checked, so the counts can still include repeats.
- 2026-11-01 08:32 UTCGHSA enrichmentGHSA-4vww-mc66-62m6 · GitHub severity MODERATE · GitHub CVSS 5.3
- 2026-11-01 08:32 UTCEG score recompute
- 2026-10-30 16:30 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-29 16:29 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-29 06:56 UTCEG score recompute
- 2026-10-29 06:56 UTCVendor advisory
- 2026-10-29 03:55 UTCOSV refresh
- 2026-10-27 16:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-25 18:27 UTCEG score recompute
- 2026-10-25 16:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-24 16:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-22 16:29 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-21 16:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-21 09:37 UTCEG score recompute
- 2026-10-21 09:37 UTCVendor advisory
- 2026-10-20 16:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-18 09:01 UTCEG score recompute
- 2026-10-16 16:33 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-14 16:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-13 16:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-12 19:16 UTCEG score recompute
- 2026-10-11 23:41 UTCEG score recompute
- 2026-10-11 13:43 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-09 20:04 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-08 22:28 UTCVendor advisory
Show 62 moreShow fewer
- 2026-10-08 21:33 UTCEG score recompute
- 2026-10-08 21:33 UTCVendor advisory
- 2026-10-07 23:44 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-05 17:40 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-10-02 17:10 UTCOSV refresh
- 2026-10-01 19:46 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-30 15:36 UTCEG score recompute▼ 0.10
- 2026-09-29 15:15 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-26 15:54 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-24 14:00 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-23 13:44 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-22 14:44 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-21 20:28 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-18 19:23 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-17 19:23 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-16 14:05 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-13 16:43 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-13 14:54 UTCOSV refresh
- 2026-09-12 14:57 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-11 09:33 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-08 21:56 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-06 13:45 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-05 15:25 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-02 14:08 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-01 13:50 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-09-01 03:32 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-30 19:14 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-30 01:19 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-28 21:37 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-26 14:42 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-25 16:34 UTCEG score recompute
- 2026-08-25 16:34 UTCVendor advisory
- 2026-08-25 13:46 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-24 14:13 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-21 23:46 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-19 23:45 UTCOSV refresh
- 2026-08-19 17:01 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-16 02:11 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-15 01:27 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-12 13:48 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-11 13:38 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-07 16:24 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-05 19:14 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-08-04 18:48 UTCOSV refresh
- 2026-07-30 16:25 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-28 15:33 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-26 14:52 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-24 14:15 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-23 14:16 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-23 02:01 UTCEG score recompute▲ 3.10
- 2026-07-22 22:48 UTCEG score recompute
- 2026-07-22 14:06 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-21 15:22 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-20 17:05 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-19 14:29 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-19 02:27 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-18 16:59 UTCOSV refresh
- 2026-07-18 10:02 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-16 17:00 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-15 16:55 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-13 06:10 UTCEPSS rescoreEPSS 75% · 99th percentile
- 2026-07-12 05:44 UTCEPSS rescoreEPSS 75% · 99th percentile
Related CVEs(same product + same vendor + same CWE)
Same product
10 shownDebian:9:tomcat8
- CVE-2020-13935NVD 7.5EG 9.0EPSS p100CRITICAL
- CVE-2020-13934NVD 7.5EG 8.4EPSS p99HIGH
- CVE-2021-41079EG 7.5EPSS p94HIGH
- CVE-2020-11996EG 7.5EPSS p98HIGH
- CVE-2021-30640EG 6.5EPSS p96MEDIUM
- CVE-2020-1935EG 4.8EPSS p95MEDIUM
- CVE-2019-17569EG 4.8EPSS p95MEDIUM
- CVE-2020-1938EG 9.8 KEVEPSS p100CRITICAL
- CVE-2020-9484NVD 7.0EG 7.9EPSS p99HIGH
- CVE-2021-25122EG 7.5EPSS p97HIGH
Same vendor
10 shownredhat:RHSA-2021:4861 · redhat:RHSA-2022:1179 · redhat:RHSA-2022:5532
- CVE-2021-30640EG 6.5EPSS p96MEDIUM
- CVE-2021-42340EG 7.5EPSS p96HIGH
- CVE-2021-41079EG 7.5EPSS p94HIGH
- CVE-2021-23840NVD 7.5EG 8.1EPSS p99HIGH
- CVE-2021-3712NVD 7.4EG 8.0EPSS p99HIGH
- CVE-2020-9484NVD 7.0EG 7.9EPSS p99HIGH
- CVE-2021-3859EG 7.5HIGH
- CVE-2021-3629NVD 5.9EG 7.5HIGH
- CVE-2021-25122EG 7.5EPSS p97HIGH
- CVE-2021-25329EG 7.0EPSS p95HIGH
Frequently asked(5)
What is CVE-2021-33037?
When was the CVE record for CVE-2021-33037 published?
Is CVE-2021-33037 actively exploited?
What is the CVSS score of CVE-2021-33037?
How do I remediate CVE-2021-33037?
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2021-33037
Is Your Infrastructure Affected by CVE-2021-33037?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.