VulnerabilityPublished 6 Nov 2026

CVE-2026-120423: undici · Improper Validation of Integrity Check Value

Affects undiciSource CVE Database V5

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Not known to be exploited · CVSS 5.9 Medium : upgrade to 8.12.4 or 7.30.2 when convenient.

Data as of 6 Nov 2026, 10:19 UTC

CVSS 3.1 base score

5.9Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (openjs)	CVSS 3.1	5.9

Patch: Available – fixed in 8.12.4, 7.30.2

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

Attack Vector: Network
Attack Complexity: High
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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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 6 Nov 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 5 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 undici to 8.12.4 or 7.30.2.

Affected software

Product	Affected	Fixed in
undiciundici	Affected >=8.0.0 <8.12.4	Fixed in 8.12.4
undiciundici	Affected >=7.15.0 <7.30.2	Fixed in 7.30.2
npmundici`pkg:npm/undici`Other threats	Affected >=7.15.0 <7.30.2 >=8.0.0 <8.12.4	Fixed in 7.30.2 8.12.4

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

AI-suggested

Upgrade undici to version 7.30.2, 8.12.4, or later where the issue is fixed. As a temporary workaround, ensure SRI integrity metadata is supplied without surrounding whitespace and use only single spaces to separate multiple digests. No other mitigation is required once patched.

Description

undici versions 7.15.0 through 7.30.1 and 8.0.0 through 8.12.3 improperly validate Subresource Integrity (SRI) metadata by splitting on a single space instead of all ASCII whitespace. This allows an attacker controlling the response body to bypass integrity checks if the integrity string contains whitespace such as tabs, leading to acceptance of tampered content without error. The issue is fixed in versions 7.30.2 and 8.12.4.

Impact

An attacker able to control the HTTP response body can bypass Subresource Integrity checks and deliver malicious or altered content without triggering an integrity error. This compromises the integrity protection that applications rely on to ensure content has not been tampered with. The vulnerability does not affect confidentiality or availability directly but impacts data integrity, potentially leading to injection of malicious code or data.

CWE-354Improper Validation of Integrity Check Value (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product does not validate or incorrectly validates the integrity check values or "checksums" of a message.
Implementation
The protocol specification describes the algorithm used for calculating the checksum. It is then a matter of implementing the calculation and verifying that the calculated checksum and the received checksum match.
OWASP Cheat Sheets
XML Security (opens in a new tab)
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
OWASP ASVS 4.0.3
V11.1.7 (opens in a new tab)
V13.3.2 (opens in a new tab)
V3.5.3 (opens in a new tab)
Attack patterns
Checksum Spoofing (opens in a new tab)
Padding Oracle Crypto Attack (opens in a new tab)
Manipulating Writeable Configuration Files (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Nov 2026, 10:19 UTC

WeaknessesCWE-354

Technical details

References

Community reviews

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