VulnerabilityPublished 2 Mar 2026Updated 9 Nov 2026

CVE-2026-3336: Aws lc sys · PKCS7_verify Certificate Chain Validation Bypass in AWS-LC

Affects aws-lc-sysSource GCVE Database

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Authoritative record:CVE-2026-3336· High 7.5

Not known to be exploited · CVSS 7.5 High : upgrade to 0.38.0 soon.

Data as of 9 Nov 2026, 11:23 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.38.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 2 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade aws-lc-sys to 0.38.0.

Affected software

Product	Affected	Fixed in
crates.ioaws-lc-sys`pkg:cargo/aws-lc-sys`Other threats	Affected >=0.24.0 <0.38.0	Fixed in 0.38.0

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AI-suggested

A patch is available in aws-lc-sys version 0.38.0 that fixes this vulnerability. Applications using aws-lc-sys should upgrade to version 0.38.0 or later. There is no workaround for this issue. Customers using AWS cloud services do not need to take any action as the vendor manages remediation for those environments.

Description

CVE-2026-3336 is a vulnerability in the AWS-LC cryptographic library's PKCS7_verify() function that allows unauthenticated users to bypass certificate chain verification when processing PKCS7 objects with multiple signers, except the final signer. This flaw affects aws-lc-sys versions from 0.24.0 up to but not including 0.38.0. The issue has been fixed in version 0.38.0. There is no workaround; users should upgrade to the latest release to mitigate this vulnerability. Customers using AWS cloud services are not required to take action as the vendor manages remediation for those services.

Impact

An unauthenticated attacker can bypass certificate chain verification for PKCS7 objects with multiple signers (except the final signer), potentially allowing the acceptance of forged or malicious certificates. This compromises the integrity of the certificate validation process in affected applications using aws-lc-sys, which could lead to trust violations in cryptographic operations relying on PKCS7 signature verification.

Summary

The vulnerability in AWS-LC's PKCS7_verify() function involves improper certificate validation that permits bypassing the certificate chain verification step for PKCS7 objects containing multiple signers, except for the final signer. This can allow an unauthenticated attacker to cause the application to accept invalid or malicious certificates, potentially leading to integrity violations. The flaw affects aws-lc-sys versions >=0.24.0 and <0.38.0. The issue is addressed in aws-lc-sys version 0.38.0. No known exploits are reported in the wild. The CVSS 3.1 base score is 7.5 (High), reflecting network attack vector, low complexity, no privileges required, no user interaction, unchanged scope, no confidentiality impact, high integrity impact, and no availability impact.

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Affected software

Description

AI analysisMachine-generated, updated 9 Nov 2026, 11:22 UTC

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