Amazon Linux 2027 Preview Security Advisory: ALAS2027-2026-237
Advisory Release Date: 2026-10-26 09:00 Pacific
Advisory Updated Date: 2026-10-26 09:00 Pacific
FAQs regarding Amazon Linux ALAS/CVE Severity
Package updates are available for Amazon Linux 2027 that fix the following vulnerabilities:
CVE-2026-97030:
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.
NOTE: https://www.openwall.com/lists/oss-security/2026/10/08/9
NOTE: https://github.com/golang/go/issues/81823
NOTE: Fixed by: https://github.com/golang/go/commit/6e2cfab0a1c1683c52f9e09270627b0c4e6446e3 (go1.27.2)
NOTE: Fixed by: https://github.com/golang/go/commit/5d84f6f08caf63b5f1300930368756bd34955f4a (go1.26.9)
CVE-2026-94448:
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-2026-94439:
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-2026-93322:
A malicious frontend can submit an LLB definition that causes buildkitd
to panic and terminate, interrupting all builds running on that daemon.
CVE-2026-93321:
A malicious frontend can submit an LLB definition that causes buildkitd
to panic and terminate, interrupting all builds running on that daemon.
CVE-2026-93320:
BuildKit may be tricked into performing file actions with special file inodes where regular files are expected. Special files may block operations or, on rootful workers, allow unintended host device access.
CVE-2026-93319:
A malicious external BuildKit frontend can send requests using the internal API that can create conditions for a data race that can cause the BuildKit daemon to panic.
CVE-2026-93318:
A malicious image can advertise DiffIDs from another image while containing different layer contents. In affected versions, BuildKit could use the advertised DiffIDs to derive cache and snapshot identity without validating that they matched the actual layer contents.
If a BuildKit daemon with shared or persistent cache first processes such a malicious image, a later build using the victim image may mount the attacker-controlled layer contents as the base image. This can allow code from the malicious image to run in the victim build, for example by replacing a commonly executed path such as /bin/sh. The attacker-controlled code may read build secrets mounted into the build, access other build resources, alter output artifacts, or hang the build.
The issue affects both regular snapshotters and lazy-pulling snapshotters such as stargz.
CVE-2026-92543:
Docker Engine classifies a registry hostname as insecure using an any-match DNS check. loadInsecureRegistries() injects 127.0.0.0/8 and ::1/128 as insecure CIDRs by default. isCIDRMatch resolves all of the hostname's addresses and returns true if a single address is in the insecure CIDR list. Because the transport re-dials the hostname rather than the CIDR-matching address, a DNS answer set of one loopback IP plus a non-loopback attacker IP disables certificate verification and enables HTTP fallback for the registry connection.
CVE-2026-92542:
The firewall rules which mark VXLAN datagrams for encryption indiscriminately match both authentic VXLAN datagrams sent from the kernel and forged datagrams sent by user processes. Any packet sent from the host network namespace of a Linux Swarm node is encrypted with the overlay-network IPsec parameters which meets the following criteria:
- UDP datagram
- Destination port is the Swarm data-path port
- Datagram starts with a VXLAN header for the VNI of an encrypted overlay network which any running container on the node is connected to
CVE-2026-81870:
OpenTelemetry-Go is the Go implementation of OpenTelemetry. From version 1.5.0 to 1.44.0, sdk/trace.NewTracerProvider emits a TracerProvider created internal Info-level diagnostic event whose MarshalLog implementations recursively include span processor, exporter, and client configuration. Applications that call otel.SetLogger to enable OpenTelemetry internal Info logging can therefore record OTLP gRPC and HTTP collector endpoints, the OTLP HTTP Insecure flag, and complete Zipkin collector URLs. A person or system with access to those logs can learn internal collector topology and can recover credentials or tokens embedded in Zipkin URL user information or query strings. The default OpenTelemetry logger does not emit the event, and this path does not log OTLP authentication headers, TLS key material, or span payloads. This issue is fixed in version 1.45.0.
CVE-2026-78667:
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-2026-78663:
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-2026-78662:
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-2026-78659:
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-2026-56855:
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-2026-10722:
A vulnerability has been found in cilium ebpf up to 0.21.0. This affects the function loadRawSpec of the file btf/btf.go of the component LoadCollectionSpec/LoadCollectionSpecFromReader. Such manipulation of the argument offset leads to integer overflow. The attack can only be performed from a local environment. The exploit has been disclosed to the public and may be used. The name of the patch is 533dfc82fd228bfadf42ea7180c39de7d9af47fa. A patch should be applied to remediate this issue.
CVE-2026-103433:
Docker Buildx Bake does not request the expected fs.read approval for certain filesystem inputs. An untrusted Bake definition can expose a readable file through a pathless secret whose ID is interpreted as a client-side pathname, or consume a local OCI image layout outside the project after entitlement validation checks a different path representation. Users who run untrusted Bake definitions are affected.
Affected Packages:
docker
Issue Correction:
Run dnf update docker or dnf update --advisory ALAS2027-2026-237 to update your system.
aarch64:
docker-debuginfo-29.9.1-1.amzn2027.0.1.aarch64
docker-29.9.1-1.amzn2027.0.1.aarch64
docker-debugsource-29.9.1-1.amzn2027.0.1.aarch64
src:
docker-29.9.1-1.amzn2027.0.1.src
x86_64:
docker-debuginfo-29.9.1-1.amzn2027.0.1.x86_64
docker-29.9.1-1.amzn2027.0.1.x86_64
docker-debugsource-29.9.1-1.amzn2027.0.1.x86_64