RHSA-2026:42079

Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

fast-uri decoded percent-encoded path separators and dot segments before applying dot-segment removal in its normalize() and equal() functions. Encoded path data was treated like real slashes and parent-directory references, so distinct URIs could collapse onto the same normalized path. Applications that normalize or compare attacker-controlled URLs to enforce path-based policy can be bypassed, with a path that appears confined under an allowed prefix normalizing to a different location. Versions <= 3.1.0 are affected. Update to 3.1.1 or later.

Validating certificate chains which use policies is unexpectedly inefficient when certificates in the chain contain a very large number of policy mappings, possibly causing denial of service. This only affects validation of otherwise trusted certificate chains, issued by a root CA in the VerifyOptions.Roots CertPool, or in the system certificate pool.

urllib3 is an HTTP client library for Python. From 2.6.0 to before 2.7.0, urllib3 could decompress the whole response instead of the requested portion (1) during the second HTTPResponse.read(amt=N) call when the response was decompressed using the official Brotli library or (2) when HTTPResponse.drain_conn() was called after the response had been read and decompressed partially (compression algorithm did not matter here). These issues could cause urllib3 to fully decode a small amount of highly compressed data in a single operation. This could result in excessive resource consumption (high CPU usage and massive memory allocation for the decompressed data) on the client side. This vulnerability is fixed in 2.7.0.

The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode("xn--example-.com") incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject "example.com" but permit "xn--example-.com". If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name "example.com".

When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a crash.

Parsing arbitrary HTML which is then rendered using Render can result in an unexpected HTML tree. This can be leveraged to execute XSS attacks in applications that attempt to sanitize input HTML before rendering.

GitPython is a python library used to interact with Git repositories. Prior to version 3.1.47, _clone() validates multi_options as the original list, then executes shlex.split(" ".join(multi_options)). A string like "--branch main --config core.hooksPath=/x" passes validation (starts with --branch), but after split becomes ["--branch", "main", "--config", "core.hooksPath=/x"]. Git applies the config and executes attacker hooks during clone. This issue has been patched in version 3.1.47.

GitPython is a python library used to interact with Git repositories. From version 3.1.30 to before version 3.1.47, GitPython blocks dangerous Git options such as --upload-pack and --receive-pack by default, but the equivalent Python kwargs upload_pack and receive_pack bypass that check. If an application passes attacker-controlled kwargs into Repo.clone_from(), Remote.fetch(), Remote.pull(), or Remote.push(), this leads to arbitrary command execution even when allow_unsafe_options is left at its default value of False. This issue has been patched in version 3.1.47.

GitPython is a python library used to interact with Git repositories. Prior to version 3.1.49, GitConfigParser.set_value() passes values to Python's configparser without validating for newlines. GitPython's own _write() converts embedded newlines into indented continuation lines (e.g. \n becomes \n\t), but Git still accepts an indented [core] stanza as a section header — so the injected core.hooksPath becomes effective configuration. Any Git operation that invokes hooks (commit, merge, checkout) will then execute scripts from the attacker-controlled path. This issue has been patched in version 3.1.49.