ALAS2023-2026-3254

References: CVE-2026-56855  CVE-2026-78659  CVE-2026-78662  CVE-2026-78663  CVE-2026-78667  CVE-2026-94439  CVE-2026-94440  CVE-2026-94448  CVE-2026-97030 
FAQs regarding Amazon Linux ALAS/CVE Severity

Issue Overview:

Previously, after a channel has been established, a malicious peer could send crafted messages that would deadlock the entire connection. Now, we handle all RFC 4254 channel messages; global requests are handled explicitly. Then, treat all other messages as a protocol error and tear the connection down instead of buffering and blocking. (CVE-2026-56855)

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. Because Request.Trailer is a map, each entry incurs memory overhead. For HTTP/2 servers, a malicious client can exploit this by sending a "Trailer" header that declares a large number of fields causing the server to allocate a disproportionate amount of memory while bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits.
This exploit is not applicable for HTTP/1 servers, which do not support multiplexing a large number of requests over one TCP connection, and whose Server.MaxHeaderBytes are calculated differently.
Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits are now applied towards the trailer fields declared in "Trailer" headers.

NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81857
NOTE: Fixed by: https://github.com/golang/go/commit/cbb0fb8b51cba866018b8a0fb4b5458f16c5c80b (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/6e049521882c944afc1e519a83971ec421dc2974 (go1.26.9) (CVE-2026-78659)

Previously, a channel registered in the mux's chanList is not usable until it is established. A malicious peer was able flood the channel's incomingRequests, deadlocking the entire connection. Now, we add an atomic established state, set when a channel becomes usable. Until such a time, handlePacket drops every packet other than the open confirmation/failure, without blocking and without tearing down the connection. (CVE-2026-78662)

The HTTP/2 server could 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 reads the buffered data.
A malicious client could exploit this to bypass the configured connection-level flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still limited by the concurrent stream limit and stream-level flow control.
The HTTP/2 server now waits to refund connection-level flow control for reset streams until after the request handler is complete.

NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81743
NOTE: Fixed by: https://github.com/golang/go/commit/31dc9e2449e394439498142451627af52626d7c4 (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/6e049521882c944afc1e519a83971ec421dc2974 (go1.26.9) (CVE-2026-78663)

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

These functions now ignore Range headers containing more than 200 ranges.
The limit is controlled by the new httpservecontentmaxranges=GODEBUG setting. Setting GODEBUG=httpservecontentmaxranges=0 disables the limit.

NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81858
NOTE: Fixed by: https://github.com/golang/go/commit/ababc3cd873d8acce1777268aa7a817e6b672028 (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/eb25b4e532c5a01f99ef860ec66743a8783f992b (go1.26.9) (CVE-2026-78667)

When an HTTP server handler sent a 2xx response to an HTTP/1 CONNECT request and returned without hijacking the connection, the server improperly continued to read and serve requests from the connection. Since a 2xx response to an HTTP/1 CONNECT converts the connection into a tunnel, the server should not treat the connection as continuing to contain HTTP.
The impact of this misbehavior is mostly limited to potential request smuggling, where an intermediate proxy considers the data on the connection to be tunneled and the server considers it to be HTTP.
The HTTP/1 server now always closes a connection after responding to a CONNECT request, regardless of the response status.

NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81744
NOTE: Fixed by: https://github.com/golang/go/commit/e92229e24a387cc006a750af176b07a459ba71a1 (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/087de1ff08ea620ac2f6ae26c939454cb793883a (go1.26.9) (CVE-2026-94439)

Parsing a multipart form could bypass memory limits and read an arbitrarily long line into memory when the remaining limit at the start of a part was less than 400 bytes. Multipart form memory limits are now properly enforced in this situation.

NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81741
NOTE: Fixed by: https://github.com/golang/go/commit/7c79b50a74b6d1aa4269b1827dda7d81f3717f9d (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/d7a7aa8e6781ddf8dce12adf60a813d957d4763e (go1.26.9) (CVE-2026-94440)

When a JavaScript template literal contains consecutive expressions, the context tracking state was not properly reset upon entering a new expression.
We now ensure that template-literal expression entries correctly reset context variables so all subsequent regular expression literals are accurately recognized and escaped.

NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81821
NOTE: Fixed by: https://github.com/golang/go/commit/b26d150e6985f804826f4fcb1aa33aa81e700b52 (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/e59c03e695f2eaa26e308f756c83773afb034e47 (go1.26.9) (CVE-2026-94448)

A trusted template author may have previously written a valid template wherein the use of the |yield| keyword would not be correctly escaped.
We now ensure that valid keyword uses are escaped and non-keyword uses are not escaped. (CVE-2026-97030)

Issue Correction:
Run dnf update skopeo --releasever 2023.12.20261026 or dnf update --advisory ALAS2023-2026-3254 --releasever 2023.12.20261026 to update your system.
More information on how to update your system can be found on this page: Amazon Linux 2023 documentation

New Packages:

aarch64:
    skopeo-debuginfo-1.22.2-1.amzn2023.0.2.aarch64
    skopeo-tests-1.22.2-1.amzn2023.0.2.aarch64
    skopeo-1.22.2-1.amzn2023.0.2.aarch64
    skopeo-debugsource-1.22.2-1.amzn2023.0.2.aarch64

src:
    skopeo-1.22.2-1.amzn2023.0.2.src

x86_64:
    skopeo-debuginfo-1.22.2-1.amzn2023.0.2.x86_64
    skopeo-1.22.2-1.amzn2023.0.2.x86_64
    skopeo-debugsource-1.22.2-1.amzn2023.0.2.x86_64
    skopeo-tests-1.22.2-1.amzn2023.0.2.x86_64

Changelog:

2026-11-11: CVE-2026-78663 was added to this advisory.

2026-11-11: CVE-2026-56855 was added to this advisory.

2026-11-11: CVE-2026-94439 was added to this advisory.

2026-11-11: CVE-2026-97030 was added to this advisory.

2026-11-11: CVE-2026-94448 was added to this advisory.

2026-11-11: CVE-2026-78662 was added to this advisory.