CVE-2026-75589

Description

Net::OAuth versions before 0.33 for Perl check HMAC-SHA1, HMAC-SHA256 and PLAINTEXT signatures with a non-constant-time comparison in verify. Each of the three compares the signature carried in the message against the locally computed one with the eq operator, which returns as soon as the two strings differ. The time taken to reject a signature varies with the length of the matching prefix. RSA-SHA1 is not affected, as it verifies through the RSA key object rather than by comparing strings. A client that can submit messages and time the replies may recover a valid signature one byte at a time rather than searching the whole signature space. Under PLAINTEXT the value compared against is the signature key itself, so the search recovers consumer_secret and token_secret.

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EPSS — Exploit Prediction

0.0018

Probability of exploitation

0.08%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-208 CWE-208

References

Other References

https://github.com/vurtdev/Net-OAuth/commit/a1a16b58add85668ef4fcda642a486ceed098eba.patch https://github.com/vurtdev/Net-OAuth/security/advisories/GHSA-g8xr-69p3-gw56 https://metacpan.org/release/RRWO/Net-OAuth-0.33/changes http://www.openwall.com/lists/oss-security/2026/08/19/3

Frequently Asked Questions

What is CVE-2026-75589? +

Net::OAuth versions before 0.33 for Perl check HMAC-SHA1, HMAC-SHA256 and PLAINTEXT signatures with a non-constant-time comparison in verify. Each of the three compares the signature carried in the message against the locally computed one with the eq operator, which returns as soon as the two strings differ. The time taken to reject a signature varies with the length of the matching prefix. RSA-SHA1 is not affected, as it verifies through the RSA key object rather than by comparing strings. A client that can submit messages and time the replies may recover a valid signature one byte at a time rather than searching the whole signature space. Under PLAINTEXT the value compared against is the signature key itself, so the search recovers consumer_secret and token_secret.

How do I check if I'm vulnerable to CVE-2026-75589? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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