Security patches (release/2.1)

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
ammonia	dependencies	patch	4.1.2 → 4.1.3
anyhow	dependencies	patch	1.0.102 → 1.0.103

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mXSS in ammonia via MathML annotation-xml encoding strip

GHSA-9jh8-v38h-cvhr / RUSTSEC-2026-0193

More information

Details

If a certain set of MathML tags are enabled, an attacker can inject arbitrary JavaScript code into the user's browser.

The annotation-xml tag has slightly different behavior than the other "integration point"
tags in MathML and SVG, but ammonia didn't handle it, so it didn't correctly
strip the namespace-incompatible tags.

This vulnerability only has an effect when the math and annotation-xml tags
are both enabled, but the encoding attribute is disabled, because it relies
on the following sequence of steps:

1. User writes code like <math><annotation-xml encoding="text/html"><gadget></annotation-xml></math>.
2. Namespace filtering checks the DOM, and it passes. <gadget> is parsed as HTML.
3. Attribute filter strips it down to <math><annotation-xml><gadget></annotation-xml></math>. Because the encoding attribute is gone, <gadget> is now parsed as MathML.
4. The gadget is written in such a way that it exploits the parsing differences between HTML and MathML.

Additionally, the gadget can only be written using a tag that is parsed as raw text in HTML.
These elements are:

• title
• textarea
• xmp
• iframe
• noembed
• noframes
• plaintext
• noscript
• style
• script

Applications that do not explicitly allow any of these tags should not be affected, since none are allowed by default.

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Discovered by: ivan0912 (YesWeHack) · Date: 2026-06-29 · Found via local differential analysis and source review of ammonia's sanitisation pipeline; no third-party systems were tested.

Severity

Unknown

References

• https://crates.io/crates/ammonia
• https://rustsec.org/advisories/RUSTSEC-2026-0193.html

This data is provided by OSV and the Rust Advisory Database (CC0 1.0).

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Unsoundness in Error::downcast_mut()

RUSTSEC-2026-0190

More information

Details

Affected versions of this crate violate borrow rules, resulting in undefined behavior, when the user adds context to an error via Error::context and then later calls Error::downcast_mut on the returned Error.

The flaw was corrected in commit 6e8c000 by revising how the mutable reference is constructed, avoiding inclusion of a shared reference in the resulting borrow chain.

Example

use anyhow::Error;
use std::fmt;

#[derive(Debug)]
struct ErrorContext(&'static str);

impl fmt::Display for ErrorContext {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt::Display::fmt(&self.0, f)
    }
}

fn main() {
    let mut error = Error::msg("inner error").context(ErrorContext("old context"));
    let context: &mut ErrorContext = error.downcast_mut().unwrap();
    context.0 = "new context";
    println!("{:?}", error);
}

Miri output

error: Undefined Behavior: trying to retag from <1538> for Unique permission at alloc602[0x38], but that tag only grants SharedReadOnly permission for this location
   --> src/ptr.rs:170:18
    |
170 |         unsafe { &mut *self.ptr.as_ptr() }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^ this error occurs as part of retag at alloc602[0x38..0x48]
    |
    = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
    = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
help: <1538> was created by a SharedReadOnly retag at offsets [0x38..0x48]
   --> src/ptr.rs:89:18
    |
 89 |             ptr: NonNull::from(ptr),
    |                  ^^^^^^^^^^^^^^^^^^
    = note: stack backtrace:
            0: anyhow::ptr::Mut::<'_, ErrorContext>::deref_mut
                at src/ptr.rs:170:18: 170:41
            1: anyhow::error::<impl anyhow::Error>::downcast_mut::<ErrorContext>
                at src/error.rs:560:18: 560:46
            2: main
                at examples/downcast_mut.rs:15:38: 15:58

Severity

Unknown

References

• https://crates.io/crates/anyhow
• https://rustsec.org/advisories/RUSTSEC-2026-0190.html
• https://github.com/dtolnay/anyhow/issues/451

This data is provided by OSV and the Rust Advisory Database (CC0 1.0).

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