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03.06.2026

Kunbus-2026-0000007: Fragnesia

TLP: WHITE

Publisher: KUNBUS PSIRT Document category: csaf_vex
Initial release date: 2026-06-03T12:43:21.710323034Z Engine: csaf-cms-backend 1.0.0
Current release date: 2026-06-03T12:43:21.710323034Z Build Date: 2026-06-03T12:41:10.348Z
Current version: 1.0.0 Status: final
CVSSv3.1 Base Score: 7.8 Severity:
Original language: Language: en-US
Also referred to:

Vulnerabilities

(CVE-2026-46300)

Description

In the Linux kernel, the following vulnerability has been resolved: net: skbuff: preserve shared-frag marker during coalescing skb_try_coalesce() can attach paged frags from @from to @to. If @from has SKBFL_SHARED_FRAG set, the resulting @to skb can contain the same externally-owned or page-cache-backed frags, but the shared-frag marker is currently lost. That breaks the invariant relied on by later in-place writers. In particular, ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(). If TCP receive coalescing has moved shared frags into an unmarked skb, ESP can see skb_has_shared_frag() as false and decrypt in place over page-cache backed frags. Propagate SKBFL_SHARED_FRAG when skb_try_coalesce() transfers paged frags. The tailroom copy path does not need the marker because it copies bytes into @to's linear data rather than transferring frag descriptors.

CWE: CWE-787:Out-of-bounds Write

Product status

Known affected
Product CVSS-Vector CVSS Base Score
KUNBUS Revolution Pi Revolution Pi OS Bookworm <= (03/2026) CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H 7.8
KUNBUS Revolution Pi Revolution Pi OS Bullseye CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H 7.8
KUNBUS Revolution Pi linux-image-revpi-v8 <= 6.12.87-revpi0-rpi-v8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H 7.8
Fixed
  • KUNBUS Revolution Pi linux-image-revpi-v8 6.12.91-revpi0-rpi-v8

Remediations

Vendor fix (2026-05-29T10:00:00.000Z)

Install Kernel Package at least 6.12.91

For products:
  • KUNBUS Revolution Pi Revolution Pi OS Bookworm <= (03/2026)
  • KUNBUS Revolution Pi linux-image-revpi-v8 6.12.91-revpi0-rpi-v8

https://packages.kunbus.com/pool/main/l/linux-revpi-v8/linux-image-revpi-v8_6.12.91-revpi0-1+deb12+1_arm64.deb

Workaround (2026-05-28T10:00:00.000Z)

Deactivate ESP Kernel Module rmmod esp4 esp6 printf 'install esp4 /bin/false\ninstall esp6 /bin/false\n' > /etc/modprobe.d/fragnesia.conf

For products:
  • KUNBUS Revolution Pi Revolution Pi OS Bookworm <= (03/2026)
  • KUNBUS Revolution Pi Revolution Pi OS Bullseye
  • KUNBUS Revolution Pi linux-image-revpi-v8 <= 6.12.87-revpi0-rpi-v8

KUNBUS PSIRT

Namespace: https://www.kunbus.com

product-security@kunbus.com

KUNBUS GmbH develops and produces the Revolution Pi Family, Revolution Pi OS and the extension modules for RevPi amongst others. KUNBUS PSIRT is responsible for vulnerability handling across all KUNBUS products and services.

References

Revision history

Version Date of the revision Summary of the revision
1.0.0 2026-06-03T12:43:21.710323034Z Initial Publication

Sharing rules

TLP:WHITE
For the TLP version see: https://www.first.org/tlp/

Legal Disclaimer

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