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CVE-2023-53600

Critical Vulnerability: CVE-2023-53600 — linux — linux_kernel

In the Linux kernel, the following vulnerability has been resolved: tunnels: fix kasan splat when generating ipv4 pmtu error If we try to emit an icmp error in response to a nonliner skb, we get BUG: KASAN: slab-out-of-bounds in ip_compute_csum+0x134/0x220 Read of size 4 at addr ffff88811c50db00 by task iperf3/1691 CPU: 2 PID: 1691 Comm: iperf3 Not tainted 6.5.0-rc3+ #309 [..] kasan_report+0x105/0x140 ip_compute_csum+0x134/0x220 iptunnel_pmtud_build_icmp+0x554/0x1020 skb_tunnel_check_pmtu

Tuesday, August 4, 2026linuxVulnios Threat Intelligence
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Vulnerability Snapshot

CVE-2023-53600 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.

Affected technology: linux_kernel.

Executive Summary

In the Linux kernel, the following vulnerability has been resolved:

tunnels: fix kasan splat when generating ipv4 pmtu error

If we try to emit an icmp error in response to a nonliner skb, we get

BUG: KASAN: slab-out-of-bounds in ip_compute_csum+0x134/0x220

Read of size 4 at addr ffff88811c50db00 by task iperf3/1691

CPU: 2 PID: 1691 Comm: iperf3 Not tainted 6.5.0-rc3+ #309

[..]

kasan_report+0x105/0x140

ip_compute_csum+0x134/0x220

iptunnel_pmtud_build_icmp+0x554/0x1020

skb_tunnel_check_pmtu+0x513/0xb80

vxlan_xmit_one+0x139e/0x2ef0

vxlan_xmit+0x1867/0x2760

dev_hard_start_xmit+0x1ee/0x4f0

br_dev_queue_push_xmit+0x4d1/0x660

[..]

ip_compute_csum() cannot deal with nonlinear skbs, so avoid it.

After this change, splat is gone and iperf3 is no longer stuck.

Why It Matters

CVE-2023-53600 is rated CRITICAL severity, requiring immediate attention from security teams.

CVSS Base Score: 9.1/10

Affected Technologies

Vendors: linux

Products: linux_kernel

🛡️What Defenders Should Check

  • Check if you are affected — Review your asset inventory for products listed in CVE-2023-53600.
  • Apply available patches — Visit vendor advisories for the latest security updates.
  • Monitor for exploitation — Check your SIEM/IDS logs for related indicators.

    • Use Vulnios to continuously monitor your exposure to CVE-2023-53600 and similar vulnerabilities.

    References & Sources

  • https://git.kernel.org/stable/c/5850c391fd7e25662334cb3cbf29a62bcbff1084
  • https://git.kernel.org/stable/c/6a7ac3d20593865209dceb554d8b3f094c6bd940
  • https://git.kernel.org/stable/c/da5f42a6e7485fbb7a6dbd6a2b3045e19e4df5cc
  • https://git.kernel.org/stable/c/e95808121953410db8c59f0abfde70ac0d34222c
  • https://git.kernel.org/stable/c/fe6a9f7516735be9fdabab00e47ef7a3403a174d

    • How Vulnios Detects This

    Vulnios scans for this vulnerability using Trivy and Grype for CVE matching against your container images and OS package manifests. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.

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    Affected Products

    linux_kernel

    Sources

    Related Threat Alerts

    Frequently Asked Questions

    What is CVE-2023-53600?

    CVE-2023-53600 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. In the Linux kernel, the following vulnerability has been resolved:

    tunnels: fix kasan splat when generating ipv4 pmtu error

    If we try to emit an icmp error in response to a nonliner skb, we get

    BU

    Am I affected?

    Check whether your environment runs linux_kernel. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.

    How urgent is the response?

    Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.

    How do I remediate?

    Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.

    Where can I track exploitation activity?

    Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2023-53600. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.

    How does Vulnios help with this?

    Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.

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