Bug 2521896 (CVE-2026-76844)
| Summary: | CVE-2026-76844 webpack-dev-middleware: webpack-dev-middleware: Information Disclosure via Path Traversal | ||
|---|---|---|---|
| Product: | [Other] Security Response | Reporter: | OSIDB Bzimport <bzimport> |
| Component: | vulnerability | Assignee: | Product Security <prodsec-ir-bot> |
| Status: | NEW --- | QA Contact: | |
| Severity: | high | Docs Contact: | |
| Priority: | high | ||
| Version: | unspecified | CC: | abarbaro, akhatavk, akostadi, alizardo, amasferr, amctagga, anjoseph, anpicker, anthomas, aoconnor, aos-team-art-private, aruklets, asdas, ataylor, bbrownin, bniver, bparees, brasmith, cdrage, cochase, dbruscin, dmayorov, doconnor, dpaolell, dranck, dschmidt, dymurray, ehelms, ehugonne, flucifre, fmariani, ggainey, gmalinko, gmeno, gparvin, groman, hasun, ibolton, janstey, jchui, jdelft, jfula, jhe, jlanda, jlledo, jmatthew, jmontleo, jowilson, jpasqual, jprabhak, jupierce, juwatts, jwong, jwon, kaycoth, kshier, ktsao, kvanderr, lchilton, lgarciaa, mbenjamin, mbiarnes, mcarlett, mdellweg, mhackett, mhulan, nboldt, nmoumoul, nyancey, oaljalju, omaciel, ometelka, osousa, pantinor, pcreech, pdelbell, pgaikwad, pjindal, ppalepu, ppostler, prdhamdh, psrna, ptisnovs, rchan, rhaigner, rhel-process-autobot, rjohnson, rstepani, rushinde, sfeifer, sghai, sidsharm, simaishi, slucidi, smallamp, sostapov, sseago, stcannon, suppawar, syedriko, tcunning, teagle, tmalecek, tsedmik, ttakamiy, vereddy, vlaad, watson-tool-maintainers, wtam, xdharmai, yfang, yguenane |
| Target Milestone: | --- | Keywords: | Security |
| Target Release: | --- | ||
| Hardware: | All | ||
| OS: | Linux | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | --- | |
| Doc Text: |
A flaw was found in webpack-dev-middleware. A remote attacker can exploit a path traversal vulnerability when the configured publicPath lacks a trailing slash. By sending a specially crafted request, the attacker can bypass a security guard, allowing the middleware to resolve files from one directory above the intended output path. This could lead to information disclosure if the middleware is configured to use the physical filesystem.
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Story Points: | --- |
| Clone Of: | Environment: | ||
| Last Closed: | Type: | --- | |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
| Bug Depends On: | 2524964, 2524965, 2524966, 2524967, 2524968, 2524969, 2524970, 2524971, 2524972 | ||
| Bug Blocks: | |||
This issue has been addressed in the following products: Red Hat Data Grid 8.6.3 Via RHSA-2026:69296 https://access.redhat.com/errata/RHSA-2026:69296 |
webpack-dev-middleware resolves a request to a local file in getFilenameFromUrl by testing the request pathname against a traversal guard and then slicing it at a fixed character offset. The guard, UP_PATH_REGEXP applied to path.normalize(`./${pathname}`), only matches ".." that stands as a whole path segment, while the containment test is the string comparison pathname.startsWith(publicPathPathname) and the file path is built as path.join(outputPath, pathname.slice(publicPathPathname.length)). When the configured publicPath has no trailing slash, a request such as GET /assets../.env against publicPath /assets yields the pathname /assets../.env, whose only dot-dot sits inside the segment "assets.." and so passes the guard, but the offset slice cuts within that segment and hands "../.env" to path.join, resolving one directory above outputPath. Reading a file from that path requires the middleware to be backed by the physical filesystem, which happens when writeToDisk is true or a custom outputFileSystem is supplied, since the default memfs volume holds only build output. Traversal depth is limited to a single directory because a separately delimited dot-dot segment is collapsed during URL parsing before the guard runs. The default publicPath value of "auto" resolves to "/" and is not affected. This is an incomplete fix for CVE-2024-29180: the guard and offset slice were introduced by that fix and are present in every release from 5.3.4, 6.1.2 and 7.1.0 onward.