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NVD / CVE Program· CNA Linux

CVE-2026-93167: csky: Fix a4/a5 restoration in syscall trace path

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.22% (FIRST EPSS).
  • Fixed version: Linux Linux 31c81b376e5f058c7f2c94f69719cf7caec2fc3f, 343aa5275484d627c921a42e8e115cae366be5de, 5.5.

Low priority for now. Upgrade to Linux Linux 31c81b376e5f058c7f2c94f69719cf7caec2fc3f, 343aa5275484d627c921a42e8e115cae366be5de, 5.5 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: csky: Fix a4/a5 restoration in syscall trace path The syscall trace path reloads syscall arguments from pt_regs before calling the syscall handler. On C-SKY ABIv2, the 5th and 6th syscall arguments are prepared as stack arguments before invoking syscallid. The current code adjusts sp before loading LSAVE_A4 and LSAVE_A5. Since those offsets are relative to the original pt_regs base, loading them after changing sp fetches the wrong slots. As a result, traced syscalls that use the 5th or 6th argument may receive corrupted arguments. This is visible with mmap2(), which takes six arguments. A small PTRACE_SYSCALL reproducer opens a file and maps one page with: mmap(NULL, 4096, PROT_READ | PROT_EXEC, MAP_PRIVATE, fd, 0) Before the fix, the traced child fails the mmap and exits with 12. After the fix, the mapping succeeds and the child exits with 0. Fix the trace path by loading a4/a5 from pt_regs before changing sp. Tested on: ck860f, linux-4.19.15, C-SKY abiv2

—No exploit Fix available
Published
Sep 17, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 12th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 108681048cf728a8570e036c34ebd7daa43133b4, 3a5837c692918c229baf63fe7950965d27c48ac2, 5.7affected
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before e9ae8e86eed68bea5d2670eadf61938a43bd2263affected · git
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before 64e3ec7a71d3b715e2567f19f64207f04999bb0caffected · git
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before 863fa63fd1491f201ac819f805a8db98d2a32c3daffected · git
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before e71a3dc5b8d2ea4d9cfbdb135d6b7777de84212eaffected · git
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before 31c81b376e5f058c7f2c94f69719cf7caec2fc3faffected · git
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before a776afa89424570bfa637ebf812ca281a5732904affected · git
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before 343aa5275484d627c921a42e8e115cae366be5deaffected · git
    • e0bbb53843b5fdfe464b099217e3b9d97e8a75d7 and later · before abb81e5ce7d995baa41556b8125fa59e28ba3be8affected · git
    • 5.4.47 and later · before 5.5affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-93165Sep 17, 2026 · platform/chrome: sensorhub: Fix memory overread in ring handler
    30Monitor
  • ← EarlierCVE-2026-93166Sep 17, 2026 · wifi: rtw89: debug: fix off by on in rtw89_ppdu_str()
    0Monitor
  • Later →CVE-2026-93168Sep 17, 2026 · dmaengine: xilinx_dma: Fix CPU stall in xilinx_dma_poll_timeout
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux31c81b376e5f058c7f2c94f69719cf7caec2fc3fVendor (CNA)
Linux Linux343aa5275484d627c921a42e8e115cae366be5deVendor (CNA)
Linux Linux5.5Vendor (CNA)
Linux Linux5.7Vendor (CNA)
Linux Linux64e3ec7a71d3b715e2567f19f64207f04999bb0cVendor (CNA)
Linux Linux863fa63fd1491f201ac819f805a8db98d2a32c3dVendor (CNA)
Linux Linuxa776afa89424570bfa637ebf812ca281a5732904Vendor (CNA)
Linux Linuxabb81e5ce7d995baa41556b8125fa59e28ba3be8Vendor (CNA)
Linux Linuxe71a3dc5b8d2ea4d9cfbdb135d6b7777de84212eVendor (CNA)
Linux Linuxe9ae8e86eed68bea5d2670eadf61938a43bd2263Vendor (CNA)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

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References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records