EUVD-2026-50231
GHSA-fr5w-2rg3-6qp3
Severity by source
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network-reachable and unauthenticated (AV:N/PR:N) but the AT:P precondition and optional-plugin dependency justify AC:H; mislabeled cached content gives I:L and unsafe decode/serving gives A:H, no confidentiality.
Primary rating from Vendor (apache).
CVSS VectorVendor: apache
Lifecycle Timeline
6DescriptionCVE.org
The Apache Traffic Server webp_transform plugin can decode unsafely and serve mislabeled, cacheable responses.
This issue affects Apache Traffic Server: from 8.0.0 through 8.1.9, from 9.0.0 through 9.2.14, from 10.0.0 through 10.1.3.
Users are recommended to upgrade to version 9.2.15 or 10.1.4, which fix the issue.
AnalysisAI
Cache poisoning and content-type confusion in the Apache Traffic Server webp_transform plugin allows remote clients to induce the proxy to decode images unsafely and store mislabeled, cacheable responses that are then served to other users. Affected releases span the 8.x (through 8.1.9), 9.x (through 9.2.14), and 10.x (through 10.1.3) branches when the optional webp_transform plugin is enabled. There is no public exploit identified at time of analysis, it is not listed in CISA KEV, and no EPSS score was provided, so risk here is driven by the CVSS 8.2 (CVSS 4.0) rating rather than observed exploitation.
Technical ContextAI
Apache Traffic Server is a high-performance forward and reverse caching HTTP proxy widely used as a CDN edge and origin-offload layer. The flaw lives in the webp_transform plugin, an optional transform module that re-encodes upstream images into WebP on the fly to reduce bandwidth. The root cause is classed as CWE-20 (Improper Input Validation): the plugin decodes image input unsafely and produces responses whose labeling (e.g., content type/cacheability metadata) does not match the actual payload, and because those responses are marked cacheable they can be stored and re-served. The CPE cpe:2.3:a:apache_software_foundation:apache_traffic_server:*:*:*:*:*:*:*:* identifies the affected product; the defect is specific to deployments that load and configure the webp_transform plugin, not to a base ATS install.
RemediationAI
Vendor-released patch: upgrade to Apache Traffic Server 9.2.15 (for the 9.x line) or 10.1.4 (for the 10.x line), as directed in the Apache advisory at https://lists.apache.org/thread/5prl9glcm9g2swnq9hqxvnokylm1gr6d; note the 8.x branch has no listed fixed release, so 8.x operators should migrate to a fixed 9.2.15+ or 10.1.4+ build. If immediate upgrade is not possible, disable or unload the webp_transform plugin from remap/plugin configuration, which fully removes the vulnerable code path at the cost of losing on-the-fly WebP transcoding (increased bandwidth/origin load). As an interim compensating control, tighten cache behavior for transformed image responses - for example, disable caching of webp_transform output or add cache-key/Vary and content-type validation at the edge - accepting the cache-hit-ratio penalty this imposes.
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Same weakness CWE-20 – Improper Input Validation
View allSame technique Information Disclosure
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External POC / Exploit Code
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