1.7

CVSS Score

4.0

-

CVSS Score

Basic Information

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CVE-2026-41677

CVE-2026-41677: rust-openssl: Out-of-bounds read in PEM password callback when user callback returns an oversized length

rust-openssl provides OpenSSL bindings for the Rust programming language. From 0.9.0 to before 0.10.78, the *_from_pem_callback APIs did not validate the length returned by the user's callback. A password callback that returns a value larger than the buffer it was given can cause some versions of OpenSSL to over-read this buffer. OpenSSL 3.x is not affected by this. This vulnerability is fixed in 0.10.78.

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2026-41677

CVE-2026-41677:

1.7

CVSS Score

4.0

-

CVSS Score

Basic Information

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Technical Details

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
openssl	rust	>= 0.9.0, < 0.10.78	0.10.78

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability is an out-of-bounds read in the PEM password callback mechanism of the rust-openssl library. The root cause lies in the openssl::util::invoke_passwd_cb function, which acts as a trampoline for handling password callbacks from the user. This function would take the length value returned by a user-provided callback and pass it directly to the native OpenSSL library without first validating that the length was within the bounds of the buffer that was provided to the callback.

The patch rectifies this by adding a check in invoke_passwd_cb. If the callback returns a length len that is greater than the buffer size size, the function now returns 0 to OpenSSL, indicating an error, thus preventing the out-of-bounds read.

The vulnerability is exposed through public API functions that use this password callback mechanism, named with the pattern *_from_pem_callback. The patch includes a test case that uses openssl::ec::EcKey::private_key_from_pem_callback to demonstrate the vulnerability and its fix. Therefore, any runtime profile during exploitation would show this function, or other similar *_from_pem_callback functions, in the call stack leading to the vulnerable invoke_passwd_cb.

Vulnerable functions

openssl::util::invoke_passwd_cb

openssl/src/util.rs

This internal function serves as a trampoline for password callbacks. Prior to the patch, it failed to validate the length returned by the user's callback against the buffer size provided. It would pass this length directly to the underlying OpenSSL library. A malicious callback could return a length larger than the buffer, leading to an out-of-bounds read in certain versions of OpenSSL.

openssl::ec::EcKey::private_key_from_pem_callback

openssl/src/ec.rs

This is a public API function that utilizes the vulnerable `invoke_passwd_cb` password callback trampoline. The vulnerability is triggered when a user provides a callback to this function that returns a length greater than the allocated buffer. The vulnerability advisory explicitly mentions that `*_from_pem_callback` APIs are affected, and this function is a concrete example demonstrated in the patch's test.

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WAF Rule

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Reasoning

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