CVE-2026-109841
undici vulnerable to Subresource Integrity bypass via non-lowercase algorithm tokens
No exploitation reported by the sources we read.
- Published2026-10-15
- Fixed in8.12.2 · 7.30.1
- WeaknessCWE-178
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
undici is an HTTP client library for Node.js. In versions 7.15.0 through 7.30.0 and 8.0.0 through 8.12.1, its fetch() implementation verifies Subresource Integrity metadata by matching the algorithm token against a lowercase-only set, even though the SRI specification defines the token by its ASCII-lowercase form, so a valid but non-lowercase token such as an uppercase or mixed-case SHA256 is treated as unknown and skipped. When no recognized algorithm remains, undici treats the integrity list as empty and accepts the response, so a server returning a body that does not match the pinned digest passes the check. An attacker who controls only the response body can therefore deliver attacker-controlled bytes to an application that pinned a valid uppercase or mixed-case SRI token, with no integrity error, affecting response integrity only. The issue is fixed in undici 7.30.1 and 8.12.2, which normalize the algorithm token to ASCII lowercase before validation, and users should upgrade to one of those versions or later. As a workaround, use lowercase algorithm tokens such as sha256, sha384, or sha512 in integrity metadata.
Timeline
dates in UTC- 2026-10-1519:17CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 18:48 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-109841?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-109841?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 8.x | ≥ 8.0.0, < 8.12.2 | 8.12.2 | NVD |
| 7.x | ≥ 7.15.0, < 7.30.1 | 7.30.1 | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Distribution builds and vendor advisories
Packages from OSV.dev and products from the vendors' CSAF advisories.
version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.
Vendor advisories
undici: undici: Subresource Integrity bypass via non-lowercase algorithm tokens
cryostat/cryostat-openshift-console-plugin-rhel9 as a component of Cryostat 4 · exploit-intelligence/vulnerability-analysis-rhel9 as a component of Exploit Intelligence · amq-broker-bin.zip as a component of Red Hat AMQ Broker 7 · +110 more
Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
Fix
- Update Nodejs undici to 8.12.2 · 7.30.1
- Vendor fix Red Hat Product Security RHSA-2026:84706 · 28 productsFor details on how to apply this update, which includes the changes described in this advisory, refer to: https://images.redhat.com/
- No fix available, says the vendor Red Hat Product Security CVE-2026-109841 · 100 productsFix deferred
- No fix available, says the vendor Red Hat Product Security CVE-2026-109841 · 10 productsAffected
- No fix planned, says the vendor Red Hat Product Security CVE-2026-109841 · 2 productsOut of support scope
- No fix planned, says the vendor Red Hat Product Security CVE-2026-109841 · 1 productWill not fix
Advisories and patches
- cna.openjsf.orgVendor Advisory
- github.comMitigation · Vendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- Published
- 2026-10-15
- Last Modified
- 2026-10-19
- NVD status
- Analyzed
Frequently asked questions
What is CVE-2026-109841?
Is CVE-2026-109841 actively exploited?
What is the CVSS score for CVE-2026-109841?
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.
- CVE-2026-102276same advisory
- CVE-2026-109869same advisoryundici vulnerable to Denial of Service via unhandled error on excessive content-encodings
- CVE-2026-109932same advisoryundici WebSocket client vulnerable to Denial of Service via unbounded automatic PONG buffering
- CVE-2026-109924same advisoryundici vulnerable to Denial of Service via unbounded memory in the EventSource parser
- CVE-2026-87029same advisoryundici vulnerable to Denial of Service via unhandled exception in the decompress interceptor
- CVE-2026-87018same advisoryundici vulnerable to Denial of Service via TLS 1.2 certificate-changing renegotiation
- CVE-2026-109383same advisoryundici vulnerable to TLS certificate validation bypass via dropped tls options in Agent
- CVE-2026-109829same advisoryundici vulnerable to cache poisoning and cross-user disclosure via cross-origin redirects