- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 25/100 · provisional
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
The Linux kernel's network buffer code (`skb_zerocopy()`) fails to pass on a shared-fragment marker, so an unprivileged user can write into the page cache of a root-owned read-only file. The flaw lies in how ESP input decrypts certain packet buffers in place, which can modify those files.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
Read the original description
In the Linux kernel, the following vulnerability has been resolved:
net: skbuff: propagate shared-frag marker in skb_zerocopy()
skb_zerocopy() moves frag descriptors from @from into @to and takes a reference on each frag, but it does not copy skb_shinfo(from)->flags into skb_shinfo(to)->flags. A destination skb holding the same page-cache backed frags as the source therefore reports skb_has_shared_frag() as false.
That breaks the invariant relied on by later in-place writers. ESP input checks skb_has_shared_frag() before deciding whether an uncloned nonlinear skb can skip skb_cow_data(); with the marker lost, an skb that skb_zerocopy() built for nfnetlink_queue or for an openvswitch upcall is decrypted in place, letting an unprivileged user write into the page cache of a root-owned read-only file.
Propagate SKBFL_SHARED_FRAG when frag descriptors are copied, as done for the other frag-transfer helpers.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure?/25Unknown. No advisory context yet
- Reach20/20Affects Linux kernel (software on nearly every server, desktop or phone)
- Severity?/10Unknown. No CVSS score or vendor rating
- No patch5/5No patch listed yet
What would change the score
- Would score about 80 if added to CISA KEV
- Would score about 75 if CISA's SSVC rates exploitation active
- Would score about 47 if advisories confirm default setups are exposed
Timeline
- CVE published
- First seen by cve.now
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
3.14
Evidence 4
- Link
- Link
- Link
- Link
Corrections
None so far.
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Questions about CVE-2026-99284
Is CVE-2026-99284 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-99284?
Linux: version 3.14.Source: cve.now feed data