01 Record

CVE-2026-75870

Punk versions before 0.18 for Perl allow session cookie forgery via an empty default HMAC key when a session is declared without a secret

CriticalPUBLISHEDCNA: CPANSec

CNA base score9.1 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

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02 Description

Punk versions before 0.18 for Perl allow session cookie forgery via an empty default HMAC key when a session is declared without a secret

03 Exploitation and scoring

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.49% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 42.1% of scored records. A rank, not a probability.

NVD base score

9.1 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

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

NVD analysis status

Deferred. NVD last modified this record on 2026-10-14.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2026-08-22 13:35Z2 MO AGO

Last updated

2026-08-25 19:28Z2 MO AGO

Reserved

2026-08-18

Assigning CNA

CPANSec

Record state

PUBLISHED

Severity

Critical (CVSS 9.1)

CNA CVSS vector

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

Weaknesses

CWE-1394Use of Default Cryptographic KeyBase

Data version

5.2

Document digest

e5f879e1ed0bf18f0a4faaa5d42fd1ba8caf3073ec9805bca8ddd6c8117773c5

05 Affected products

No products listed

This record names no affected vendor or product. That is common for reserved identifiers and for records whose CNA published only a narrative description.

06 References

metacpan.orghttps://metacpan.org/release/LNATION/Punk-0.17/source/include/punk/punk_session.htechnical-description
metacpan.orghttps://metacpan.org/release/LNATION/Punk-0.17/view/lib/Punk.pmtechnical-description
metacpan.orghttps://metacpan.org/release/LNATION/Punk-0.18/source/Changesrelease-notes
www.openwall.comhttp://www.openwall.com/lists/oss-security/2026/08/22/5

07 Remediation

Upgrade to Punk 0.18 or later.