CVE WatchAug 22, 2026

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.

CVSS

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No CVSS

EPSS

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KEV

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Exploit Today

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0-100

Published: Aug 22, 2026 · Last modified: Aug 22, 2026 · CWE-1394

EPSS · 30d

Not enough EPSS history yet.

Technical 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. The session keyword freezes its options onto the application as given: it does not require a secret, warn, or refuse to start when one is absent. The cookie read and the write-back both default that key to the empty string, so a declaration with no secret option, or with an undefined or empty one, signs and verifies with a zero-length HMAC-SHA256 key. An attacker who knows the cookie format can then mint one offline carrying any contents the session holds, such as a user identifier or a role. Nothing marks the misconfiguration at runtime: cookies are well formed and sessions round-trip as expected.

Official references

Related CVEs

CVECVSSEPSSKEVRExploitTitleMod.

CVE-2026-548874.8 MED

15.8%

——5Use of Default Cryptographic Key vulnerability in Erlang/OTP ssl (DTLS server) allows predictable DTLS cookie computation during the startup window, enabling source address verification bypass. On DTLS server startup, dtls_server_connection:initial_hello/3 initializes previous_cookie_secret to the empty binary (<<>>) instead of a random value. Because HMAC with an empty key is deterministic, anyone who observes the plaintext ClientHello can compute dtls_handshake:cookie(<<>>, IP, Port, Hello) and forge a valid DTLS cookie before the first rotation of the cookie secret. The DTLS cookie (RFC 6347 §4.2.1) is a denial-of-service mitigation that prevents spoofed source IPs from forcing the server to allocate state and perform expensive cryptographic operations; it is not an authentication mechanism. During the window from server startup until the first secret rotation (0 to 15 seconds), an attacker who can observe the plaintext ClientHello can bypass the source address verification, enabling DTLS handshake amplification with spoofed source addresses. This vulnerability is associated with program file lib/ssl/src/dtls_server_connection.erl and program routine dtls_server_connection:initial_hello/3. This issue affects OTP from OTP 20.0 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 8.2 before 11.7.3, 11.6.0.3 and 11.2.12.10.29d CVE-2026-207096.6 MED

1.5%

——0Use of Default Cryptographic Key in the hardware for some Intel(R) Pentium(R) Processor Silver Series, Intel(R) Celeron(R) Processor J Series, Intel(R) Celeron(R) Processor N Series may allow an escalation of privilege. Hardware reverse engineer adversary with a privileged user combined with a high complexity attack may enable escalation of privilege. This result may potentially occur via physical access when attack requirements are present with special internal knowledge and requires no user interaction. The potential vulnerability may impact the confidentiality (high), integrity (none) and availability (none) of the vulnerable system, resulting in subsequent system confidentiality (high), integrity (high) and availability (none) impacts.28d