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Apache Tomcat EUVDEUVD-2026-85226

| CVE-2026-77756 LOW
HTTP Request/Response Smuggling (CWE-444)
2026-09-23 apache GHSA-gpfr-7w77-mp48
3.7
CVSS 3.1 · Vendor: apache

Severity by source

Vendor (apache) PRIMARY
3.7 LOW
AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
vuln.today AI
3.7 LOW

Network-reachable and unauthenticated (PR:N), but AC:H because it needs a fronting proxy with divergent TE parsing; impact is a single failed request, so A:L only, no C/I.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (apache).

CVSS VectorVendor: apache

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

Lifecycle Timeline

4
Metadata Corrected
Sep 23, 2026 - 12:40 vuln.today
tag: Java added
Metadata Corrected
Sep 23, 2026 - 12:40 vuln.today
tag: Information Disclosure removed
Analysis Generated
Sep 23, 2026 - 11:51 vuln.today
CVE Published
Sep 23, 2026 - 11:18 cve.org
LOW

DescriptionCVE.org

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.

AnalysisAI

HTTP request desynchronization in Apache Tomcat allows an unauthenticated remote attacker to cause a single request belonging to another user to fail when Tomcat is deployed behind a reverse proxy. The flaw (CWE-444) arises because Tomcat processes the Transfer-Encoding header on HTTP/1.0 requests, and when a fronting proxy interprets that header differently, the two sides disagree about request boundaries on a shared upstream connection. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Exploit
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Execution
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Impact
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Vulnerability AssessmentAI

Exploitation Exploitable only when Apache Tomcat is deployed behind a reverse proxy AND the proxy interprets the Transfer-Encoding header on HTTP/1.0 requests differently than Tomcat does - the desynchronization arises from that interpretation gap. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment This is a low-severity availability issue, not the 'Information Disclosure' the tag implies. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Vendor-released patch: upgrade to Apache Tomcat 11.0.26, 10.1.60, or 9.0.122, which contain the fix; installations on 8.5.67 through 8.5.100 must migrate to a supported branch (9.0.122 or later) because the 8.5.x line was already end-of-life when this CVE was assigned and will not receive a fix. … Detailed patch versions, workarounds, and compensating controls in full report.

Threat intelligence, references, and detailed analysis are available after sign-in.

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EUVD-2026-85226 vulnerability details – vuln.today

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