update to go1.25.6

[vvoland]

• https://github.com/golang/go/issues?q=milestone%3AGo1.25.6+label%3ACherryPickApproved
• full diff: golang/go@go1.25.5...go1.25.6

This releases includes 6 security fixes following the security policy:

• archive/zip: denial of service when parsing arbitrary ZIP archives

  archive/zip used a super-linear file name indexing algorithm that is invoked the first time a file in an archive is opened. This can lead to a denial of service when consuming a maliciously constructed ZIP archive.

  Thanks to Thanks to Jakub Ciolek for reporting this issue.

  This is CVE-2025-61728 and Go issue https://go.dev/issue/77102.

• net/http: memory exhaustion in Request.ParseForm

  When parsing a URL-encoded form net/http may allocate an unexpected amount of
  memory when provided a large number of key-value pairs. This can result in a
  denial of service due to memory exhaustion.

  Thanks to jub0bs for reporting this issue.

  This is CVE-2025-61726 and Go issue https://go.dev/issue/77101.

• crypto/tls: Config.Clone copies automatically generated session ticket keys, session resumption does not account for the expiration of full certificate chain

  The Config.Clone methods allows cloning a Config which has already been passed
  to a TLS function, allowing it to be mutated and reused.

  If Config.SessionTicketKey has not been set, and Config.SetSessionTicketKeys has
  not been called, crypto/tls will generate random session ticket keys and
  automatically rotate them. Config.Clone would copy these automatically generated
  keys into the returned Config, meaning that the two Configs would share session
  ticket keys, allowing sessions created using one Config could be used to resume
  sessions with the other Config. This can allow clients to resume sessions even
  though the Config may be configured such that they should not be able to do so.

  Config.Clone no longer copies the automatically generated session ticket keys.
  Config.Clone still copies keys which are explicitly provided, either by setting
  Config.SessionTicketKey or by calling Config.SetSessionTicketKeys.

  This issue was discoverd by the Go Security team while investigating another
  issue reported by Coia Prant (github.com/rbqvq).

  Additionally, on the server side only the expiration of the leaf certificate, if
  one was provided during the initial handshake, was checked when considering if a
  session could be resumed. This allowed sessions to be resumed if an intermediate
  or root certificate in the chain had expired.

  Session resumption now takes into account of the full chain when determining if
  the session can be resumed.

  Thanks to Coia Prant (github.com/rbqvq) for reporting this issue.

  This is CVE-2025-68121 and Go issue https://go.dev/issue/77113.

• cmd/go: bypass of flag sanitization can lead to arbitrary code execution

  Usage of 'CgoPkgConfig' allowed execution of the pkg-config
  binary with flags that are not explicitly safe-listed.

  To prevent this behavior, compiler flags resulting from usage
  of 'CgoPkgConfig' are sanitized prior to invoking pkg-config.

  Thank you to RyotaK (https://ryotak.net) of GMO Flatt Security Inc.
  for reporting this issue.

  This is CVE-2025-61731 and go.dev/issue/77100.

• cmd/go: unexpected code execution when invoking toolchain

  The Go toolchain supports multiple VCS which are used retrieving modules and
  embedding build information into binaries.

  On systems with Mercurial installed (hg) downloading modules (e.g. via go get or
  go mod download) from non-standard sources (e.g. custom domains) can cause
  unexpected code execution due to how external VCS commands are constructed.

  On systems with Git installed, downloading and building modules with malicious
  version strings could allow an attacker to write to arbitrary files on the
  system the user has access to. This can only be triggered by explicitly
  providing the malicious version strings to the toolchain, and does not affect
  usage of @latest or bare module paths.

  The toolchain now uses safer VCS options to prevent misinterpretation of
  untrusted inputs. In addition, the toolchain now disallows module version
  strings prefixed with a "-" or "/" character.

  Thanks to splitline (@splitline) from DEVCORE Research Team for reporting this
  issue.

  This is CVE-2025-68119 and Go issue https://go.dev/issue/77099.

• crypto/tls: handshake messages may be processed at the incorrect encryption level

  During the TLS 1.3 handshake if multiple messages are sent in records that span
  encryption level boundaries (for instance the Client Hello and Encrypted
  Extensions messages), the subsequent messages may be processed before the
  encryption level changes. This can cause some minor information disclosure if a
  network-local attacker can inject messages during the handshake.

  Thanks to Coia Prant (github.com/rbqvq) for reporting this issue.

  This is CVE-2025-61730 and Go issue https://go.dev/issue/76443

View the release notes for more information:
https://go.dev/doc/devel/release#go1.25.6

- What I did

- How I did it

- How to verify it

- Description for the changelog

Update Go runtime to [1.25.6](https://go.dev/doc/devel/release#go1.25.6)

- A picture of a cute animal (not mandatory but encouraged)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[thaJeztah]

LGTM