CISA Adds Three Known Exploited Vulnerabilities to Catalog

ownCloud Server versions from 10.6.0 up to (but not including) 10.13.1 accept WebDAV pre-signed URLs even when no signing key is configured for the file owner, an improper authentication flaw (CWE-287). A remote attacker who knows a victim's username can therefore access, modify, or delete that user's files without any credentials, with no privileges or user interaction required (CVSS 9.8). Any organization running a self-hosted ownCloud Server instance in the affected version range is exposed, especially internet-facing deployments. CISA added the flaw to its Known Exploited Vulnerabilities catalog on 2026-08-27, confirming exploitation in the wild, and EPSS assigns a 43.2% probability of exploitation within 30 days (99th percentile). No public proof-of-concept code is known, but recent press reports of attacks against ownCloud (including theft of records at a Philippine research body) indicate active targeting of ownCloud flaws.

Do: Upgrade to ownCloud Server 10.13.1 or later immediately, prioritizing internet-facing instances, as the flaw is on CISA's KEV list with BOD 26-04 patching deadlines. Until patched, configure signing keys for users where possible and restrict internet exposure of the pre-signed URL/WebDAV endpoints, and review server logs for unauthenticated file access, modification, or deletion tied to known usernames. If mitigations are not available for a given deployment, follow BOD 26-04 guidance for cloud services or discontinue use of the product.

CVE-2026-53362 is an out-of-bounds write (CWE-787) in the Linux kernel's IPv6 output path: __ip6_append_data() mis-accounts fraggap bytes on the paged-allocation branch, leaving the new skb's linear area undersized so the copy of carried-over fragment-gap data spills past skb->end into the trailing skb_shared_info. An unprivileged local user can trigger the corruption by sending over a UDPv6 socket using MSG_MORE combined with MSG_SPLICE_PAGES; the bad accounting was introduced by commit 773ba4fe9104 ('ipv6: avoid partial copy for zc') and became triggerable when commit ce650a166335 allowed the MSG_SPLICE_PAGES case to proceed instead of returning -EINVAL. Successful triggering causes kernel memory corruption that, per the high confidentiality/integrity/availability scores, can lead to loss of data confidentiality, integrity and availability — potentially local privilege escalation or a system crash. Any Linux system running a kernel with the affected code is exposed; the source data provides no specific affected version numbers, only the introducing and trigger commits. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-08-27, indicating known in-the-wild exploitation (ransomware use unknown), with EPSS at 0.5% and no public PoC known.

Do: Apply the kernel fix per vendor instructions: upgrade to Linux kernel builds containing the fraggap-accounting resolution for __ip6_append_data(), following CISA's BOD 26-04 patching requirements (for cloud services, follow BOD guidance or discontinue use if mitigations are unavailable); no fixed version numbers were provided in the source data, so confirm with your distribution/vendor that the fix commit is included. Until patched, prioritize multi-user hosts and systems where untrusted local users can open UDPv6 sockets, since exploitation requires local unprivileged access with MSG_MORE and MSG_SPLICE_PAGES. Track KEV-required remediation deadlines, as the flaw is cataloged as exploited in the wild (added 2026-08-27).

CVE-2026-66384 is a directory/path-restriction bypass (CWE-22) in JFrog Artifactory in which an authenticated user can write data outside the intended Docker cache path when specific remote-repository conditions are met. The attack is carried out over the network using valid low-privilege credentials and requires no user interaction, but the triggering conditions are specific enough that the CVSS vector rates exploit complexity as high. A successful attacker gains unauthorized modification of files outside the cache directory (integrity impact only per the CVSS vector, with no confidentiality or availability impact scored), potentially tampering with stored content or system files depending on the deployment. Any organization running JFrog Artifactory with Docker remote repositories is potentially affected. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2026-08-27, confirming exploitation in the wild; no public proof-of-concept is known and ransomware use is not confirmed.

Do: Check JFrog's security advisory for CVE-2026-66384 and upgrade Artifactory to the fixed release it specifies (no version numbers are provided in the available data). Because the flaw is on the CISA KEV list (added 2026-08-27), federal agencies must remediate per BOD 26-04 timelines or discontinue use, and all operators should review Docker remote-repository configurations for the triggering conditions and audit for unexpected writes outside the Docker cache path. Restricting authenticated Artifactory access to trusted users and CI systems limits exposure while patching is completed.