undici vulnerable to Subresource Integrity bypass via whitespace in integrity metadata
- Exploited
- No known exploitation
- Fix
- Fixed in 7.30.2, 8.12.4
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 7.30.2, 8.12.4.
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 23/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
undici, an HTTP client for Node.js, contains a flaw in how fetch checks Subresource Integrity metadata, letting an attacker who controls a response body supply bytes that pass verification when the pinned value includes leading or surrounding whitespace. The bug can be reached remotely, without logging in, and it lets an attacker alter the content an application receives without triggering an integrity error.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
undici is an HTTP client for Node.js. In versions 7.15.0 through 7.30.1 and 8.0.0 through 8.12.3, fetch verifies Subresource Integrity metadata by splitting the integrity string on a single space, but the SRI grammar separates metadata by ASCII whitespace, which also includes the horizontal tab. An integrity value whose digest is preceded by a tab or other ASCII whitespace is parsed as a single unrecognized token and skipped, and when no recognized algorithm remains undici treats the integrity list as empty and accepts the response, so a server returning a body different from the pinned digest passes the check. An application that pins a response with a valid but whitespace-surrounded SRI value receives attacker-controlled bytes with no integrity error, and the attacker needs only to control the response body, not the integrity metadata. The issue is fixed in undici 7.30.2 and 8.12.4, and users should upgrade to one of those versions or later. As a workaround, supply SRI integrity metadata without surrounding whitespace, using a single space to separate multiple digests.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Unknown: No advisory context yet
- Reach?/20Unknown. No tracked technology or package matched
- Severity5.9/10CVSS 5.9
- No patch0/5No signal
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 28 if advisories confirm default setups are exposed
What to do
Upgrade to a fixed version: 7.30.2, 8.12.4.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- undici undici
From 7.15.0 · fixed in 7.30.2; From 8.0.0 · fixed in 8.12.4
Evidence 2
- Advisory
- Link
Corrections
None so far.
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Questions about CVE-2026-120423
Is CVE-2026-120423 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-120423?
undici: from 7.15.0 before 7.30.2; from 8.0.0 before 8.12.4.Source: cve.now feed data
How do I fix CVE-2026-120423?
Upgrade to a fixed version: 7.30.2, 8.12.4.Source: cve.now feed data