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CVE-2026-72889

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify

9.8 CriticalFix available

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify.

verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed.

A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.45%Up 0.3 points since Aug 19, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.8

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify.

verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed.

A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.

Record
CVE-2026-72889
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-347, CWE-757
Updated
2026-11-02
EUVDEUVD-2026-62347 9.8

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify.

verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed.

A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.

Record
EUVD-2026-62347
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
NVD 9.8

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify.

verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed.

A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.

Record
CVE-2026-72889
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-347, CWE-757
Updated
2026-11-02
OSV 9.8

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify.

verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed.

A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.

Record
CVE-2026-72889
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-347, CWE-757
Updated
2026-11-02
OSVDEBIAN-CVE-2026-72889 9.8

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify. verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed. A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.

Record
DEBIAN-CVE-2026-72889
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-72889 9.8

Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm in verify. verify resolves the signature method class from the signature_method parameter of the incoming message. signature_method is required on every request, so the algorithm used to check a signature is chosen by whoever sent it, and nothing lets the verifying party pin the method instead. When a message names HMAC-SHA1 or HMAC-SHA256, the key is derived from consumer_secret and token_secret rather than from the key the provider deployed. A provider deployed on RSA-SHA1 holds only the consumer public key, and RFC 5849 does not use consumer_secret for that method, so the required parameter is filled with a placeholder. A client that names HMAC-SHA1 instead has its signature checked against that placeholder, so a guessable one is enough to forge requests for any consumer key and token.

Record
UBUNTU-CVE-2026-72889
CVSS 3.1
9.8 CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVMGASA-2026-0365 No score

Updated perl-Net-OAuth packages fix security vulnerabilities

Net::OAuth::Client versions before 0.32 for Perl allow the service provider to silently downgrade OAuth 1.0a to OAuth 1.0 in get_request_token Net::OAuth versions before 0.32 for Perl allow memory exhaustion via unbounded caching of failed module loads in smart_require Net::OAuth versions before 0.33 for Perl allow the sender to choose the signature algorithm 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

Record
MGASA-2026-0365
Updated
2026-11-02
OSVopenSUSE-SU-2026:11551-1 No score

perl-Net-OAuth-0.330.0-1.1 on GA media

These are all security issues fixed in the perl-Net-OAuth-0.330.0-1.1 package on the GA media of openSUSE Tumbleweed.

Record
openSUSE-SU-2026:11551-1
Updated
2026-11-02

Affected packages

Affected packages
PackageAffectedFixed
libnet-oauth-perl
Debian:12
All versions, plus listed versions
0.28-40.30-10.31-10.31-20.32-10.33-1
None known
libnet-oauth-perl
Debian:13
All versions, plus listed versions
0.31-10.31-20.32-10.33-1
None known
libnet-oauth-perl
Debian:14
before 0.33-1, plus listed versions
0.31-10.31-20.32-1
0.33-1
perl-Net-OAuth
Mageia:10
From an advisory covering 4 CVEs
before 0.330.0-1.mga10
0.330.0-1.mga10
perl-Net-OAuth
Mageia:9
From an advisory covering 4 CVEs
before 0.330.0-1.mga9
0.330.0-1.mga9
libnet-oauth-perl
Ubuntu:16.04:LTS
All versions, plus listed versions
0.28-2
None known
libnet-oauth-perl
Ubuntu:18.04:LTS
All versions, plus listed versions
0.28-2
None known
libnet-oauth-perl
Ubuntu:20.04:LTS
All versions, plus listed versions
0.28-3
None known
libnet-oauth-perl
Ubuntu:22.04:LTS
All versions, plus listed versions
0.28-3
None known
libnet-oauth-perl
Ubuntu:24.04:LTS
All versions, plus listed versions
0.28-4
None known
libnet-oauth-perl
Ubuntu:26.10
All versions, plus listed versions
0.31-10.33-1
None known
libnet-oauth-perl
Ubuntu:26.04:LTS
All versions, plus listed versions
0.31-1
None known
perl-Net-OAuth
openSUSE:Tumbleweed
From an advisory covering 4 CVEs
before 0.330.0-1.1
0.330.0-1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-72889 is a critical vulnerability (CVSS 9.8) in libnet-oauth-perl, published August 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.45%, the 39th percentile. Fixed in libnet-oauth-perl 0.33-1.

References

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