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Security Digest · Vulnerability record

CVE-2026-41293: Apache Tomcat - HTTP/2 request headers not validated

Improper Input Validation vulnerability in Apache Tomcat.

CVSS 9.8 Critical EPSS 1.7% · p77

Updated By erroneo.us Security Desk17 references Seen in the digest for May 12, 2026

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

  • No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
  • EPSS 1.7%, percentile 77: FIRST’s model estimates a 1.7% chance of exploitation activity in the next 30 days, higher than 77% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
  • Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
  • Only applies if your dependency tree includes org.apache.tomcat.embed:tomcat-embed-core (Maven) >= 10.1.0-M1, < 10.1.55, fixed in 10.1.55; org.apache.tomcat.embed:tomcat-embed-core (Maven) >= 11.0.0-M1, < 11.0.22, fixed in 11.0.22; org.apache.tomcat:tomcat (Maven) >= 10.1.0-M1, < 10.1.55, fixed in 10.1.55; org.apache.tomcat:tomcat (Maven) >= 11.0.0-M1, < 11.0.22, fixed in 11.0.22. Check your lockfile, including transitive dependencies.

What it is

Improper Input Validation vulnerability in Apache Tomcat. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.21, from 10.1.0-M1 through 10.1.54, from 9.0.0.M1 through 9.0.117, from 10.0.0-M1 through 10.0.27. Older, end of support versions may also be affected. Users are recommended to upgrade to version [FIXEDVERSION], which fixes the issue.

From the GitHub advisory

Versions Affected: Apache Tomcat 11.0.0-M1 to 11.0.21 Apache Tomcat 10.1.0-M1 to 10.1.54 Apache Tomcat 9.0.0.M1 to 9.0.117 Older, unsupported versions may also be affected

Description: HTTP/2 request headers were not validated which may have triggered unexpected application behaviour if the application (quite reasonably) assumed that header value exposed through the Servlet API would be specification compliant.

Mitigation: Users of the affected versions should apply one of the following mitigations: - Upgrade to Apache Tomcat 11.0.22 or later - Upgrade to Apache Tomcat 10.1.55 or later - Upgrade to Apache Tomcat 9.0.118 or later

Credit: This issue was identified by Dawit Jeong (@dawitngoliath)

Weakness type: CWE-20.

Product: org.apache.tomcat.embed:tomcat-embed-core (Maven) · Assigned by: apache · Published: 2026-05-12

Affected and fixed versions

EcosystemPackageVulnerableFirst fixed
Mavenorg.apache.tomcat.embed:tomcat-embed-core>= 10.1.0-M1, < 10.1.5510.1.55
Mavenorg.apache.tomcat.embed:tomcat-embed-core>= 11.0.0-M1, < 11.0.2211.0.22
Mavenorg.apache.tomcat:tomcat>= 10.1.0-M1, < 10.1.5510.1.55
Mavenorg.apache.tomcat:tomcat>= 11.0.0-M1, < 11.0.2211.0.22
Mavenorg.apache.tomcat.embed:tomcat-embed-core>= 8.5.0, < 9.0.1189.0.118
Mavenorg.apache.tomcat:tomcat>= 8.5.0, < 9.0.1189.0.118
Mavenorg.apache.tomcat:tomcat-coyote>= 8.5.0, < 9.0.1189.0.118
Mavenorg.apache.tomcat:tomcat-coyote>= 10.1.0-M1, < 10.1.5510.1.55
Mavenorg.apache.tomcat:tomcat-coyote>= 11.0.0-M1, < 11.0.2211.0.22
VendorProductAffected versions (per CVE record)
Apache Software FoundationApache Tomcat11.0.0-M1 <= 11.0.21, 10.1.0-M1 <= 10.1.54, 9.0.0.M1 <= 9.0.117, 10.0.0-M1 <= 10.0.27, 8.5.0 <= 8.5.100

Severity scores

Scored byCVSSScoreVector
CISA-ADP3.19.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub3.19.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
  • Attack vector: network (remotely reachable)
  • Attack complexity: low
  • Privileges required: none (no login)
  • User interaction: none
  • Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

  • CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
  • CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
  • FIRST EPSS (model of 2026-10-21): 1.68% probability of exploitation activity in the next 30 days; percentile 77.

Timeline

  • — CVE record published by apache
  • — GitHub-reviewed advisory GHSA-r29c-68gh-xp6x published (critical)
  • — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

  1. lists.apache.org lists.apache.org

Vulnerability records

  1. GitHub Advisory GHSA-r29c-68gh-xp6x github.com
  2. CVE.org record CVE-2026-41293 cve.org
  3. NVD entry CVE-2026-41293 nvd.nist.gov

Other references from the CVE record and advisory

  1. openwall.com openwall.com
  2. github.com github.com
  3. github.com github.com
  4. github.com github.com
  5. github.com github.com
  6. github.com github.com
  7. github.com github.com
  8. github.com github.com
  9. github.com github.com
  10. github.com github.com
  11. tomcat.apache.org tomcat.apache.org
  12. tomcat.apache.org tomcat.apache.org
  13. tomcat.apache.org tomcat.apache.org

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