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Red Hat Security Advisory

RHSA-2026:87041

golang security, bug fix, and enhancement update

Released 2026-10-21 · Red Hat rating Important · View on Red Hat →

Fixed in

Fixes 15 records

Priority MEDIUM 49

The HTTP/2 server can refund connection-level flow control twice for the same data: Once when a client resets a stream (refunding data for any sent-but-unread portion of the stream), and again when a request handler read…

CVSS 3.1CRITICAL 9.1 Network No auth No interaction EPSS 0.00858 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 +1 CWE-675
Priority MEDIUM 40

Multiple ECH outer extension references are not permitted under RFC 9849; previously, a client could send a well-crafted packet that could trigger memory exhaustion in the server process by specifying multiple references…

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00716 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-405
Priority MEDIUM 40

Parsing a multipart form can bypass memory limits and read an arbitrarily long line into memory when the remaining limit at the start of a part is less than 400 bytes.

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00706 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-770
Priority MEDIUM 40

A malicious HTTP/2 peer can cause excessive CPU consumption in the client or server by opening a large number of streams and then sending many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values.

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00847 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 +1 CWE-405
Priority MEDIUM 40

When parsing a Range header containing a large number of small ranges, FileServer(FS), ServeContent, and ServeFile(FS) can consume an excessive amount of CPU.

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00663 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-770
Priority MEDIUM 40

Historically, we have been rather lax about malformed framing-related headers in our HTTP/2 implementation, as they cannot interfere with HTTP/2 framing.

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00542 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 +1 CWE-444
Priority MEDIUM 40

When "Trailer" headers are sent by a client, the HTTP server internally uses the header values to populate the Request.Trailer map passed to the server handler.

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00866 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 +1 CWE-405
Priority MEDIUM 40

When http.Transport sends an HTTP/1 CONNECT request with a non-empty Request.Body, it writes the body directly to the connection without framing after the request headers.

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00604 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-444
Priority LOW 39

When an HTTP server handler sends a 2xx response to an HTTP/1 CONNECT request and returns without hijacking the connection, the server improperly continues to read and serve requests from the connection.

CVSS 3.1HIGH 7.5 Network No auth No interaction EPSS 0.00528 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-444
Priority LOW 35

Previously, a user operating inside of a malicious Go project that defines a bogus golang.org/toolchain go.sum entry and operates a malicious GOMODPROXY the user chooses to use can bypass the intended checksum.

CVSS 3.1HIGH 7.8 Local No auth User interaction EPSS 0.00102 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-354
Priority LOW 35

Previously, a user operating inside of a malicious Go project that defines a bogus golang.org/fips140 and operates a malicious GOMODPROXY the user chooses to connect to can serve an arbitrary module in its place.

CVSS 3.1HIGH 7.8 Local No auth User interaction EPSS 0.00097 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-354
Priority LOW 27

A trusted template author may have previously written a valid template wherein the use of the 'yield' keyword would not be correctly escaped.

CVSS 3.1MEDIUM 6.1 Network No auth User interaction EPSS 0.00289 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-79
Priority LOW 27

When a JavaScript template literal contains consecutive expressions, the context tracking state was not properly reset upon entering a new expression.

CVSS 3.1MEDIUM 6.1 Network No auth User interaction EPSS 0.00289 Published 2026-10-08 Partial fix · 1.26.9, 1.27.2 CWE-79