CVE-2026-6291
MediumCVSS 6.5Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
Bleichenbacher padding oracle vulnerability in PKCS#7 KTRI decryption in wolfSSL. When decrypting PKCS#7 EnvelopedData using RSA PKCS#1 v1.5 key transport, the library returned distinguishable error codes depending on whether RSA padding validation failed or the decrypted content was malformed. This allowed an attacker to incrementally recover the Content Encryption Key (CEK) by observing error responses.
Risk Assessment
An attacker can exploit this vulnerability to recover the Content Encryption Key (CEK), compromising the confidentiality of data protected by PKCS#7 EnvelopedData. The risk is particularly high in environments where the attacker can repeatedly send crafted messages and observe responses.
Recommendation
Immediately update wolfSSL to a version containing the fix, which generates a deterministic pseudo-random fake CEK on padding failure and proceeds with decryption in constant-time, ensuring all failure paths return the same error.
Related vulnerabilities
- CVE-2026-113364Critical
Buffer overflow in the data receiving process in NEC WebSAM WinShare versions 7.5.0 and earlier, 7.6.0, and 7.7.0 through 7.7.2 on Windows allows a remote unauthenticated attacker to execute arbitrary code with SYSTEM privileges via a crafted packet with a malformed data size value in the protocol header.
- CVE-2026-113363Critical
Improper input validation in the network communication processing in NEC WebSAM WinShare versions 7.2.0 through 7.5.0, 7.6.0, and 7.7.0 through 7.7.2 on Windows allows a remote unauthenticated attacker to execute arbitrary commands with SYSTEM privileges via a crafted network packet sent to the computer running WinShare.
- CVE-2026-124560Critical
A vulnerability was found in D-Link DIR-878 version 1.20B05 in the GetCAPTCHAsetting function of bin/prog.cgi (HNAP Handler component). Manipulating the uid argument results in a heap-based buffer overflow. The attack can be initiated remotely and the exploit has been made public.
- CVE-2026-119506Critical
The Frontend Admin by DynamiApps plugin (acf-frontend-form-element) through version 3.30.1 contains an incorrect privilege assignment vulnerability. The flaw allows an attacker to escalate privileges within the WordPress site.
- CVE-2026-6715Critical
IBM Concert 1.0 through 3.0.1.1 allows an attacker to supply crafted input that is incorporated into an operating system command without adequate validation or sanitization. Successful exploitation allows remote attackers to execute arbitrary commands on the underlying operating system with the privileges of the affected service.
- CVE-2026-17466Critical
IBM Optim versions 1.0.0, 1.1.0, and 1.2.0 are vulnerable to path traversal, allowing a remote authenticated attacker to obtain sensitive information.
- CVE-2026-15266Critical
IBM Concert 1.0 through 3.0.1.1 contains components that allow potentially unsafe command execution, which could be exploited to run arbitrary system commands on the host.
- CVE-2026-114464Critical
IBM Process Mining 2.0.0 through 2.2.1 has improper access control, which could allow a remote attacker to obtain sensitive information.
- CVE-2026-107331Critical
IBM DataStage on Cloud Pak for Data 5.4.0.0 has an absolute-path traversal vulnerability that could allow a remote authenticated attacker to obtain sensitive information.
- CVE-2026-109900Critical
The Melapress Role Editor plugin for WordPress (through version 1.3.0) contains an incorrect privilege assignment vulnerability that allows privilege escalation. A low-privileged user can gain a higher level of access within the system.
Original NVD description (English source)
Bleichenbacher padding oracle in PKCS#7 KTRI decryption. When decrypting PKCS#7 EnvelopedData using RSA PKCS#1 v1.5 key transport, wolfSSL returned distinguishable error codes depending on whether RSA padding validation failed versus whether the decrypted content was malformed. An attacker able to submit crafted EnvelopedData messages and observe error responses could use this as a padding oracle to incrementally recover the encrypted Content Encryption Key (CEK). The fix generates a deterministic pseudo-random fake CEK on padding failure (via HMAC-SHA256) and proceeds with decryption identically, using constant-time operations throughout, so that all failure paths produce the same error regardless of padding validity.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS