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CVE-2026-77756— Apache Tomcat: Transfer-Encoding honored for HTTP/1.0 requests

Quick assessment

Affected
Apache Software Foundation Apache Tomcat
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Apache Tomcat 中存在“HTTP 请求/响应走私”漏洞，属于“HTTP 请求不一致解释”类安全问题。该漏洞源于 Tomcat 在处理 HTTP/1.0 请求的 Transfer-Encoding 头时行为不一致。当 Tomcat 位于反向代理之后时，攻击者可能利用此漏洞，导致其他用户的请求失败。 受影响版本： Apache Tomcat 11.0.0-M1 至 11.0.25 Apache Tomcat 10.1.0-M1 至 10.1.59 Apache Tomcat 9.0.47 至 9.0.121

AI Predicted 5.3 Difficulty: Moderate EPSS 0.53% · P45

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 5

VendorProduct Version RangeStatus
Apache Software Foundation Apache Tomcat 11.0.0-M1≤ 11.0.25 affected
10.1.0-M1≤ 10.1.59 affected
9.0.47≤ 9.0.121 affected
8.5.67≤ 8.5.100 affected
≤ 7.0.109 unaffected
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I. Basic Information for CVE-2026-77756

Vulnerability Information
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Vulnerability Title
Apache Tomcat: Transfer-Encoding honored for HTTP/1.0 requests
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
HTTP请求的解释不一致性(HTTP请求私运)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Apache Software Foundation Apache Tomcat 11.0.0-M1 ~ 11.0.25 -

II. Public POCs for CVE-2026-77756

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III. Intelligence Information for CVE-2026-77756

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Mailing List Discussions for CVE-2026-77756 (1)

Same Patch Batch · Apache Software Foundation · 2026-09-23 · 25 CVEs total

CVE-2026-31377 7.5 HIGH Apache Doris: Improper Authentication Allows Unauthorized Access to FE Meta Service
CVE-2026-86247 Apache Tomcat Native: Client certificate requirements can be down-graded
CVE-2026-82331 Apache BuildStream: tar source extraction escape
CVE-2026-86246 Apache Tomcat Native: Insecure OpenSSL options enabled
CVE-2026-86243 Apache Tomcat Native: DoS via TLS handshake
CVE-2026-87022 Apache Tomcat: WebSocket message smuggling with per-message-deflate
CVE-2026-86350 Apache Tomcat: Regression in fix for CVE-2026-41293 can trigger request header mix-up
CVE-2026-86248 Apache Tomcat: Fix for CVE-2026-34500 was incomplete. OCSP checks sometimes soft-fail with
CVE-2026-79677 Apache Tomcat: WebSocket DoS due to lost asynchronous write timeout
CVE-2026-78437 Apache Tomcat: HTTP/2 DoS via malformed request
CVE-2026-78383 Apache Tomcat: AJP DoS via missing request body
CVE-2026-77791 Apache Tomcat: DoS via busy wait during WebSocket close
CVE-2026-77762 Apache Tomcat: Stale HPACK emitter injects trailers into recycled pooled Request
CVE-2026-76183 Apache Tomcat: Bypass of security constraints for WebSocket endpoints
CVE-2026-75973 Apache Tomcat: Cross-context authentication mix-up with Jakarta Authentication configured
CVE-2026-73581 Apache Tomcat: OpenSSL and OpenSSL-FFM TLS implementations ignore CRLs when certificate us
CVE-2026-94243 Apache Sling Security Bundle: RefererFilter accepts weaker-than-origin evidence
CVE-2026-94251 Apache Sling Security Bundle: ContentDispositionFilter mediates only one address/API shape
CVE-2026-91928 Apache Sling XSS: Sanitizer bypass, uncontrolled resource consumption and failure pf prote
CVE-2026-96443 Apache Doris: JDBC driver URL validation bypass leads to remote code execution

Showing top 20 of 25 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: Apache Tomcat
Same vendor: Apache Software Foundation
Same weakness: CWE-444