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Response snapshot Oct 27, 2026, 13:16 UTC

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VulnerabilityCVE-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.

Net::OAuth versions before 0.33 for Perl check HMAC-SHA1, HMAC-SHA256 and PLAINTEXT signatures with a non-constant-time comparison in verify.

Published Updated

At a glance

Exploited
Not known
Severity
7.5 High (CVSS 3.1)
Chance of exploitation
Not estimated
Sources
1 source

What to do

Check the vendor advisory for affected versions and fixes.

Read NVD CVE-2026-75589 (opens a new tab)

What happened

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.

Scores and how they were measured

CVSS base severity

7.5

Version 3.1As of

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Measurement source (opens a new tab)

How bad it is if exploited. Not a prediction of exploitation or proof you are exposed.

EPSS probability

Not available

A model's estimate of exploitation in the next 30 days, not certainty or your own risk.

Sources

  1. Primary source

    NVD CVE-2026-75589 (opens a new tab)

    NVD record: description, CVSS (the CNA score is preferred), affected products, and publication date. Not evidence of exploitation.

    Published Checked

  2. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

  3. Primary source

    NVD CVE API 2.0 (opens a new tab)

    The NVD API page that supplied this CVE record.

    Published Date not suppliedChecked

Cite this record

For factual claims, cite the primary sources above; cite KEVWire for its compilation, dates, and classifications.

APA

KEVWire. (2026, October 27). Net::OAuth versions before 0.33 for Perl check HMAC-SHA1, HMAC-SHA256 and PLAINTEXT signatures with a non-constant-time comparison in verify. (CVE-2026-75589). https://kevwire.com/record/CVE-2026-75589

MLA

"Net::OAuth versions before 0.33 for Perl check HMAC-SHA1, HMAC-SHA256 and PLAINTEXT signatures with a non-constant-time comparison in verify. (CVE-2026-75589)." KEVWire, 27 Oct. 2026, kevwire.com/record/CVE-2026-75589.

Chicago

KEVWire. "Net::OAuth versions before 0.33 for Perl check HMAC-SHA1, HMAC-SHA256 and PLAINTEXT signatures with a non-constant-time comparison in verify. (CVE-2026-75589)." Last modified October 27, 2026. https://kevwire.com/record/CVE-2026-75589.

Evidence summary (plain text)

Net::OAuth versions before 0.33 for Perl check HMAC-SHA1, HMAC-SHA256 and PLAINTEXT signatures with a non-constant-time comparison in verify. (Aug 19, 2026).
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.
CVSS 7.5 (version 3.1; evidence as of Oct 27, 2026; https://nvd.nist.gov/vuln/detail/CVE-2026-75589).
Sources:
NVD CVE-2026-75589: https://nvd.nist.gov/vuln/detail/CVE-2026-75589
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-27T11:21:04.532Z&lastModEndDate=2026-10-27T12:50:57.384Z&resultsPerPage=500&startIndex=0
NVD CVE API 2.0: https://services.nvd.nist.gov/rest/json/cves/2.0?lastModStartDate=2026-10-27T10:50:59.514Z&lastModEndDate=2026-10-27T12:20:55.240Z&resultsPerPage=500&startIndex=0
Record ID: CVE-2026-75589.
Record origin: Ingested record.
AI evidence: Not assessed.
Known exploitation: Not assessed.
Zero-day status: Not assessed. KEV membership alone does not establish zero-day status.
About this data

This record was ingested from a data source. Retrieved: Oct 27, 2026, 12:50 UTC. Ingestion is not an independent editorial investigation.

NVD status: Deferred. Publication in the NVD is not evidence of exploitation.

A CISA KEV listing documents known exploitation, not necessarily a zero-day; absence from the catalog does not prove a vulnerability has never been exploited.

Technology tags indicate possible relevance, not verified exposure. Confirm the affected product, version, and configuration against your own inventory; KEVWire does not scan your systems.

A personal reading checklist on this device, not verified remediation.

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