Linux Kernel Out-of-Bounds Write Vulnerability
In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: make ebt_snat ARP rewrite writable The ebtables SNAT target keeps the Ethernet source address rewrite behind skb_ensure_writable(skb, 0). This is…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 2 / 5
- KEV catalog (CISA)18 Sept 2026
- Exploited in EUVD (ENISA)18 Sept 2026
- Used by ransomwareno
- EPSS above 10 %0.93%
- No account, over the networkno
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
In the Linux kernel, the following vulnerability has been resolved: netfilter: bridge: make ebt_snat ARP rewrite writable The ebtables SNAT target keeps the Ethernet source address rewrite behind skb_ensure_writable(skb, 0). This is intentional: at the bridge ebtables hooks the Ethernet header is addressed through skb_mac_header()/eth_hdr(), while skb->data points at the Ethernet payload. Asking skb_ensure_writable() for ETH_HLEN bytes would check the payload, not the Ethernet header, and would reintroduce the small packet regression fixed by commit 63137bc5882a. However, the optional ARP sender hardware address rewrite is different. It writes through skb_store_bits() at an offset relative to skb->data: skb_store_bits(skb, sizeof(struct arphdr), info->mac, ETH_ALEN) skb_header_pointer() only safely reads the ARP header; it does not make the later sender hardware address range writable. If that range is still held in a nonlinear skb fragment backed by a splice-imported file page, skb_store_bits() maps the frag page and copies the new MAC address directly into it. Ensure the ARP SHA range is writable before reading the ARP header and before calling skb_store_bits().
Affected products
- 63137bc5882a1882c553d389fdeeeace86ee1741 <afd64b59c3de9bbbdd3759e834fdc55cda716e0b
- patch: 0
- 5.4.73 <5.5
- b7d23c2c87584eb429f115c078ed511be8b18e29
- 63137bc5882a1882c553d389fdeeeace86ee1741 <67ba971ae02514d85818fe0c32549ab4bfa3bf49
- 5.9.2 <5.10
- patch: 5.10.259
- 63137bc5882a1882c553d389fdeeeace86ee1741 <153ea96c806aea395daba907a4f88480b6ad5093
- 63137bc5882a1882c553d389fdeeeace86ee1741 <76280b78cc9f23bdc6438e10ad6dff148ef8375b
- 63137bc5882a1882c553d389fdeeeace86ee1741 <c9b5ff59feffb92a147a84a5aa28acd2cb8ff4c5
- 5.10
- patch: 6.12.94
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
References
Other exploited vulnerabilities from the same vendor
- CVE-2026-46300Linux Kernel Missing Initialization of a Variable Vulnerability5.4 · Rising fast
- CVE-2025-39964Linux Kernel Race Condition Vulnerability4.4 · Actively exploited
- CVE-2025-39682Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability5.8 · Actively exploited
- CVE-2026-53362Linux Kernel Unspecified Vulnerability4.3 · Actively exploited
- CVE-2022-0995Linux Kernel Out-of-Bounds Write Vulnerability4.6 · Actively exploited
- CVE-2022-0492Linux Kernel Improper Authentication Vulnerability4.5 · Actively exploited