VulnerabilityPublished 2 Mar 2026Updated 9 Nov 2026

CVE-2026-3338: Aws lc sys · PKCS7_verify Signature Validation Bypass in AWS-LC

Affects aws-lc-sysSource GCVE Database

Compare

Authoritative record:CVE-2026-3338· 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 56% 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

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

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

Description

CVE-2026-3338 is a high-severity vulnerability in the aws-lc-sys library, specifically in the PKCS7_verify() function of AWS-LC. It allows an unauthenticated attacker to bypass signature verification when processing PKCS7 objects with Authenticated Attributes. This flaw affects aws-lc-sys versions from 0.24.0 up to, but not including, 0.38.0. There is no workaround; users should upgrade to version 0.38.0 or later. Customers of AWS cloud services are not impacted and do not need to take action.

Impact

An unauthenticated attacker can bypass signature verification in affected versions of aws-lc-sys, potentially allowing the acceptance of forged signatures. This compromises the integrity of signature validation processes relying on PKCS7_verify(), which could lead to unauthorized actions or acceptance of malicious data. There is no impact on confidentiality or availability.

Summary

The vulnerability in aws-lc-sys (CVE-2026-3338) arises from improper signature validation in the PKCS7_verify() function of AWS-LC. This flaw enables unauthenticated users to bypass signature verification for PKCS7 objects containing Authenticated Attributes, potentially allowing maliciously crafted signatures to be accepted as valid. The issue affects aws-lc-sys versions >=0.24.0 and <0.38.0. The vulnerability has a CVSS 3.1 base score of 7.5, indicating high severity with network attack vector, low attack complexity, no privileges required, and no user interaction needed. The integrity impact is high, with no confidentiality or availability impact. A fix is available in aws-lc-sys version 0.38.0.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

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

Technical details

References

Community reviews

Related threats