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CVE-2026-77756

Apache Tomcat: Transfer-Encoding honored for HTTP/1.0 requests

LOW
3.7
CVSS Score
Published: September 23, 2026 at 11:18 AM UTC
Updated: September 23, 2026 at 07:30 PM UTC
1 product affected across 1 vendorTomcat

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Severity
LOW3.7
Exploit prediction
EPSS 0.5%
SSVC
No known exploit

Description

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Apache Tomcat caused by processing the transfer-encoding header for an HTTP/1.0 request may allow an attacker to cause one request from another user to fail when Tomcat is located behind a reverse proxy. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.25, from 10.1.0-M1 through 10.1.59, from 9.0.47 through 9.0.121. The following versions were EOL at the time the CVE was created but are known to be affected: from 8.5.67 through 8.5.100. Other unsupported versions may also be affected. Users are recommended to upgrade to version 11.0.26, 10.1.60 or 9.0.122, which fix the issue.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Tomcat· Apache
60%
10.1.0-M1 ≤ v ≤ 10.1.5911.0.0-M1 ≤ v ≤ 11.0.258.5.67 ≤ v ≤ 8.5.1009.0.47 ≤ v ≤ 9.0.12110.1.0-M111.0.0-M18.5.679.0.47
Vendor states this is fixed in 7.0.109 (unaffected)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

Vendor Advisory
Source: [email protected]
https://lists.apache.org/thread/bl5b6rxqh3vb2k9bj2794vhor7o6xl3z
Source: af854a3a-2127-422b-91ae-364da2661108
http://www.openwall.com/lists/oss-security/2026/09/23/22

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

3.7LOWCISA-ADP
Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
LOW
Vector?

Quick Info

StatusAWAITING ANALYSIS
CWE
CWE-444

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