The Rust Security Response WG was notified that the regex crate did not properly limit the complexity of the regular expressions (regex) it parses. An attacker could use this security issue to perform a denial of service, by sending a specially crafted regex to a service accepting untrusted regexes. No known vulnerability is present when parsing untrusted input with trusted regexes.

This issue has been assigned CVE-2022-24713. The severity of this vulnerability is "high" when the regex crate is used to parse untrusted regexes. Other uses of the regex crate are not affected by this vulnerability.

Overview

The regex crate features built-in mitigations to prevent denial of service attacks caused by untrusted regexes, or untrusted input matched by trusted regexes. Those (tunable) mitigations already provide sane defaults to prevent attacks. This guarantee is documented and it's considered part of the crate's API.

Unfortunately a bug was discovered in the mitigations designed to prevent untrusted regexes to take an arbitrary amount of time during parsing, and it's possible to craft regexes that bypass such mitigations. This makes it possible to perform denial of service attacks by sending specially crafted regexes to services accepting user-controlled, untrusted regexes.

Affected versions

All versions of the regex crate before or equal to 1.5.4 are affected by this issue. The fix is include starting from regex 1.5.5.

Mitigations

We recommend everyone accepting user-controlled regexes to upgrade immediately to the latest version of the regex crate.

Unfortunately there is no fixed set of problematic regexes, as there are practically infinite regexes that could be crafted to exploit this vulnerability. Because of this, we do not recommend denying known problematic regexes.

Acknowledgements

We want to thank Addison Crump for responsibly disclosing this to us according to the Rust security policy, and for helping review the fix.

We also want to thank Andrew Gallant for developing the fix, and Pietro Albini for coordinating the disclosure and writing this advisory.

On Windows, configuring a named pipe server with pipe_mode will force ServerOptions::reject_remote_clients as false.

This drops any intended explicit configuration for the reject_remote_clients that may have been set as true previously.

The default setting of reject_remote_clients is normally true meaning the default is also overridden as false.

Workarounds

Ensure that pipe_mode is set first after initializing a ServerOptions. For example:

let mut opts = ServerOptions::new();
opts.pipe_mode(PipeMode::Message);
opts.reject_remote_clients(true);

Summary

In the AES GCM implementation of decrypt_in_place_detached, the decrypted ciphertext (i.e. the correct plaintext) is exposed even if tag verification fails.

Impact

If a program using the aes-gcm crate's decrypt_in_place* APIs accesses the buffer after decryption failure, it will contain a decryption of an unauthenticated input. Depending on the specific nature of the program this may enable Chosen Ciphertext Attacks (CCAs) which can cause a catastrophic breakage of the cipher including full plaintext recovery.

Details

As seen in the implementation of decrypt_in_place_detached for AES GCM, if the tag verification fails, an error is returned. Because the decryption of the ciphertext is done in place, the plaintext contents are now exposed via buffer.

This should ideally not be the case - as noted in page 17 of NIST's publication Recommendation for Block Cipher Modes of Operation: Galois/Counter Mode (GCM) and GMAC:

In Step 8, the result of Step 7 is compared with the authentication tag that was received as an input: if they are identical, then the plaintext is returned; otherwise,FAIL is returned.

This is seems correctly addressed in the AES GCM SIV implementation, where the decrypted buffer is encrypted again before the error is returned - this fix is straightforward to implement in AES GCM. To ensure that these types of cases are covered during testing, it would be valuable to add test cases like 23, 24 etc from project wycheproof to ensure that when a bad tag is used, there is an error on decryption and that the plaintext value is not exposed.

PoC

To reproduce this issue, I'm using test case 23 from project wycheproof.

    let key = GenericArray::from_slice(&hex!("000102030405060708090a0b0c0d0e0f"));
    let nonce = GenericArray::from_slice(&hex!("505152535455565758595a5b"));
    let tag = GenericArray::from_slice(&hex!("d9847dbc326a06e988c77ad3863e6083")); // bad tag
    let mut ct = hex!("eb156d081ed6b6b55f4612f021d87b39");
    let msg = hex!("202122232425262728292a2b2c2d2e2f");
    let aad = hex!("");
    let cipher = Aes128Gcm::new(&key);
    let _plaintext = cipher.decrypt_in_place_detached(&nonce, &aad, &mut ct, &tag);
    assert_eq!(ct, msg);

Previous versions of tracing-subscriber were vulnerable to ANSI escape sequence injection attacks. Untrusted user input containing ANSI escape sequences could be injected into terminal output when logged, potentially allowing attackers to:

• Manipulate terminal title bars
• Clear screens or modify terminal display
• Potentially mislead users through terminal manipulation

In isolation, impact is minimal, however security issues have been found in terminal emulators that enabled an attacker to use ANSI escape sequences via logs to exploit vulnerabilities in the terminal emulator.

This was patched in PR #3368 to escape ANSI control characters from user input.

In versions 0.4.44 and below of tar-rs, when unpacking a tar archive, the tar crate's unpack_dir function uses fs::metadata() to check whether a path that already exists is a directory. Because fs::metadata() follows symbolic links, a crafted tarball containing a symlink entry followed by a directory entry with the same name causes the crate to treat the symlink target as a valid existing directory — and subsequently apply chmod to it. This allows an attacker to modify the permissions of arbitrary directories outside the extraction root.

This issue has been fixed in version 0.4.45.

Versions 0.4.44 and below of tar-rs have conditional logic that skips the PAX size header in cases where the base header size is nonzero.

As part of CVE-2025-62518, the astral-tokio-tar project was changed to correctly honor PAX size headers in the case where it was different from the base header. This is almost the inverse of the astral-tokio-tar issue.

Any discrepancy in how tar parsers honor file size can be used to create archives that appear differently when unpacked by different archivers. In this case, the tar-rs (Rust tar) crate is an outlier in checking for the header size — other tar parsers (including e.g. Go archive/tar) unconditionally use the PAX size override. This can affect anything that uses the tar crate to parse archives and expects to have a consistent view with other parsers.

This issue has been fixed in version 0.4.45.