This CVE represents a code-path defect, not a systemic authentication failure. The key technical distinction: COPY and MOVE operations bypass authorization checks while other WebDAV methods (PUT, DELETE, GET) enforce them correctly. This points to a bug in how these two specific operations inherit session state from a shared handler, rather than an entire service lacking authentication. The compound nature of COPY and MOVE (read-then-write) amplifies the risk—an attacker gains unauthorized read access to whatever resources the WebDAV service can reach, followed by unauthorized write to a destination they control, in a single atomic operation they shouldn't be able to perform at all. On a SOHO router running as root—where configuration state, VPN credentials, and captive portal tokens often reside—this translates to a potential lateral movement primitive through the device's own datastore, not merely 'copying a file.' The seventeen-model affected roster spanning MT2500/MT3000 through BE10000, all sharing 4.8.x as the vulnerable baseline, indicates the flaw lives in shared library code that got replicated without independent security review across hardware generations. This pattern mirrors a known vulnerability genotype in embedded WebDAV implementations where COPY and MOVE become 'forgotten operations'—implemented for RFC compliance but rarely tested, making them susceptible to authorization drift during subsequent code changes. Verify whether WebDAV is enabled and restrict it to trusted networks; disable if unused. Monitor logs for anomalous COPY/MOVE operations. The vendor has confirmed the vulnerability but hasn't published remediation timing—treat this as a pending patch and prioritize network segmentation controls in the interim.
CVE-2026-19979
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA vulnerability was identified in GL.iNet A1300, AX1800, AXT1800, BE1400, BE3600, BE6500, BE9300, BE10000, E5800, MT2500, MT3000, MT3600BE, MT5000, MT6000, X2000, X3000 and XE3000 up to 4.8.x. Affected by this vulnerability is the function COPY/MOVE of the component WebDAV Service. Such manipulation leads to authorization bypass. It is possible to launch the attack remotely. The vendor explains: "After our investigation, we have confirmed that the vulnerability described (...) does indeed exist."
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisThe application confirms who you are but does not properly check whether you are permitted to perform a given action, so authenticated users reach functions or data meant for others. Attackers test roles and object references to find the gap. Remediation is an authorization check on every request, evaluated against the acting user's actual permissions.
General guidance for the improper authorization class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataThere is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.
Free. We build fixes in the order the community asks for them — and we’ll tell you the moment this one lands.
We develop and verify an original fix where the vendor hasn’t, from $4,900. Deployed to your staging first — never straight to production.
Scope it with usSee what else the community needs solved on the solutions-needed board.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-19979 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesThis CVE represents a code-path defect, not a systemic authentication failure. The key technical distinction: COPY and MOVE operations bypass authorization checks while other WebDAV methods (PUT, DELETE, GET) enforce them correctly. This points to a bug in how these two specific operations inherit session state from a shared handler, rather than an entire service lacking authentication. The compound nature of COPY and MOVE (read-then-write) amplifies the risk—an attacker gains unauthorized read access to whatever resources the WebDAV service can reach, followed by unauthorized write to a destination they control, in a single atomic operation they shouldn't be able to perform at all. On a SOHO router running as root—where configuration state, VPN credentials, and captive portal tokens often reside—this translates to a potential lateral movement primitive through the device's own datastore, not merely 'copying a file.' The seventeen-model affected roster spanning MT2500/MT3000 through BE10000, all sharing 4.8.x as the vulnerable baseline, indicates the flaw lives in shared library code that got replicated without independent security review across hardware generations. This pattern mirrors a known vulnerability genotype in embedded WebDAV implementations where COPY and MOVE become 'forgotten operations'—implemented for RFC compliance but rarely tested, making them susceptible to authorization drift during subsequent code changes. Verify whether WebDAV is enabled and restrict it to trusted networks; disable if unused. Monitor logs for anomalous COPY/MOVE operations. The vendor has confirmed the vulnerability but hasn't published remediation timing—treat this as a pending patch and prioritize network segmentation controls in the interim.
Practitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-19979 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data