7.5

CVE-2020-13935: apache tomcat Loop with Unreachable Exit Condition

Modified
AliasesRHSA-2020:3383UBUNTU-CVE-2020-13935DEBIAN-CVE-2020-13935
Published 14-07-2020Last modified 08-10-2026

Vulnerability summary

CVE-2020-13935 is a high (CVSS 7.5) Loop with Unreachable Exit Condition vulnerability in apache tomcat. EPSS estimates a 86.61% chance of exploitation in the next 30 days, higher than 99.7% of scored vulnerabilities.

Priority
Prioritisesevere

Severe, CVSS 7.5 (NVD); no exploitation reported by the 5 checked sources; EPSS 87% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
86.61%
0%100%
Critical · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 20 · Related 12
DLA-2286-1DSA-4727-1MGASA-2020-0331OPENSUSE-SU-2020:1102-1OPENSUSE-SU-2020:1111-1OPENSUSE-SU-2024:12103-1

Timeline

  1. 14-07-2020
    PublishedVulnerability first disclosed.
  2. 08-10-2026
    Last modifiedVulnerability information updated.

Description

The payload length in a WebSocket frame was not correctly validated in Apache Tomcat 10.0.0-M1 to 10.0.0-M6, 9.0.0.M1 to 9.0.36, 8.5.0 to 8.5.56 and 7.0.27 to 7.0.104. Invalid payload lengths could trigger an infinite loop. Multiple requests with invalid payload lengths could lead to a denial of service.

CVSS metrics

6 scores · 5 sources · 2 versions

EPSS trend

Probability

86.61%

Chance of exploitation in the next 30 days

Percentile

100%

Versus all other CVEs

30-day change

No change 0.00 pp

From 86.61% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Oracle12 products
Ubuntu3 products
  • tomcat7All versions (No fix recorded)
  • tomcat8< 8.0.32-1ubuntu1.13 | All versions (No fix recorded)
  • tomcat9All versions (No fix recorded) | < 9.0.31-1ubuntu0.1
Debian2 products
Org.apache.tomcat2 products
  • tomcat≥ 10.0.0-M1, < 10.0.0-M7 | ≥ 9.0.0.M1, < 9.0.37 | ≥ 8.5.0, < 8.5.57 | ≥ 7.0.27, < 7.0.105
  • tomcat-websocket≥ 10.0.0-M1, < 10.0.0-M7 | ≥ 9.0.0.M1, < 9.0.37 | ≥ 8.5.0, < 8.5.57 | ≥ 7.0.27, < 7.0.105
Apache1 product
  • tomcatEOL≥ 7.0.27, ≤ 7.0.104 | ≥ 8.5.0, ≤ 8.5.56 | ≥ 9.0.1, ≤ 9.0.36 | 9.0.0:milestone1 | 9.0.0:milestone10 | 9.0.0:milestone11 | 9.0.0:milestone12 | 9.0.0:milestone13 | 9.0.0:milestone14 | 9.0.0:milestone15 | 9.0.0:milestone16 | 9.0.0:milestone17 | 9.0.0:milestone18 | 9.0.0:milestone19 | 9.0.0:milestone2 | 9.0.0:milestone20 | 9.0.0:milestone21 | 9.0.0:milestone22 | 9.0.0:milestone23 | 9.0.0:milestone24 | 9.0.0:milestone25 | 9.0.0:milestone26 | 9.0.0:milestone27 | 9.0.0:milestone3 | 9.0.0:milestone4 | 9.0.0:milestone5 | 9.0.0:milestone6 | 9.0.0:milestone7 | 9.0.0:milestone8 | 9.0.0:milestone9 | 10.0.0:milestone1 | 10.0.0:milestone2 | 10.0.0:milestone3 | 10.0.0:milestone4 | 10.0.0:milestone5 | 10.0.0:milestone6
Canonical1 product
Mcafee1 product
  • epolicy_orchestrator5.9.0 | 5.9.1 | 5.10.0 | 5.10.0:update_1 | 5.10.0:update_2 | 5.10.0:update_3 | 5.10.0:update_4 | 5.10.0:update_5 | 5.10.0:update_6 | 5.10.0:update_7 | 5.10.0:update_8
Netapp1 product
Opensuse1 product
Org.apache.tomcat.embed1 product
  • tomcat-embed-websocket≥ 7.0.27, < 7.0.105 | ≥ 8.5.0, < 8.5.57 | ≥ 9.0.0.M1, < 9.0.37 | ≥ 10.0.0-M1, < 10.0.0-M7
Redhat1 product
  • jbossweb< 0:7.5.31-2.Final_redhat_2.1.ep6.el5 | < 0:7.5.31-2.Final_redhat_2.1.ep6.el6 | < 0:7.5.31-2.Final_redhat_2.1.ep6.el7

11 vendors · 26 products

References

49 links
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