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CVE.org (no NVD analysis yet)· CNA Linux

CVE-2026-98840: vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF

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: 0.17% (FIRST EPSS).
  • Fixed version: Linux Linux 1485a3dd97ab1af2605243cabe6b604546d46dd1, 226bd5603371cd9f6642cbb9e9a677f445de3530, 233a2e190b12884d186027d0b86d43a48799b69c; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1.

Low priority for now. Upgrade to Linux Linux 1485a3dd97ab1af2605243cabe6b604546d46dd1, 226bd5603371cd9f6642cbb9e9a677f445de3530, 233a2e190b12884d186027d0b86d43a48799b69c; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.159.1-1 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: vc_screen: reload vc pointer before if (ret) in vcs_write() to avoid UAF The reload of 'vc' added by commit 8fb9ea65c9d1 ("vc_screen: reload load of struct vc_data pointer in vcs_write() to avoid UAF") sits after the 'if (ret)' block, so the copy-failure break path exits the loop without reloading vc. If the vc was kfree()'d via vc_port_destruct during the unlocked copy_from_user() window, the post-loop 'if (written && vc) vcs_scr_updated(vc)' is reached with a stale non-NULL vc. The '&& vc' guard from commit a287620312dc ("vc_screen: fix null-ptr-deref in vcs_notifier() during concurrent vcs_write") only handles the NULL case, not this stale-non-NULL case; vcs_notifier() then reads param->vc->vc_num from freed memory: BUG: KASAN: slab-use-after-free in vcs_notifier+0x7c/0xd0 Read of size 2 at addr ffff888007149190 Call Trace: vcs_notifier+0x7c/0xd0 atomic_notifier_call_chain+0x70/0xa0 vcs_scr_updated+0x77/0xa0 vcs_write+0x71b/0x7e0 Allocated by task: vc_allocate -> con_install -> tty_open Freed by task: kfree <- vt_ioctl (VT_DISALLOCATE -> vc_port_destruct) Move the reload to immediately after console_lock(), before 'if (ret)', so every break path below passes a fresh vc to the post-loop vcs_scr_updated().

—No exploit Fix available
Published
Oct 18, 2026
Updated
Oct 30, 2026
EPSS
0.1% · 7th 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 · 0.1%

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Noroxi analysis

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Affected systems

Is your version affected?

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—

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

    • 74be188eb2dc1c99d63986167b9a67d415fe7326, 09a43e81279b8da15526da09877134b8bcf618b0, 7.2affected
    • 43a6281790273c1b0a9ab76609ff0245b968f1e6 and later · before cbc05413d3694193494b2374b56bae801ac41fecaffected · git
    • b6bbb85cf45bf0b070e741997fe0af3a772c5ad5 and later · before 942742000a0288d4ca60c448894aabacd48004d5affected · git
    • ff4806202749a51938236214adc0281481a57366 and later · before c9f56d4b29792a62b17f2051ba93fd3b40a479ecaffected · git
    • 8232fca738011ca2ec865b46ec721d1796dc0580 and later · before c073d01f6f5367c3a4f07efd507274ed0d03acd0affected · git
    • 73049768ad57145acd337102c5aa3c788e6642c8 and later · before 1485a3dd97ab1af2605243cabe6b604546d46dd1affected · git
    • 7cc3dd79777f6ae4625ec37e84dd18a26dc88bde and later · before 233a2e190b12884d186027d0b86d43a48799b69caffected · git
    • a287620312dc6dcb9a093417a0e589bf30fcf38a and later · before 9dfcadc5e003fb250dd471db90144bd5366140e9affected · git
    • a287620312dc6dcb9a093417a0e589bf30fcf38a and later · before 226bd5603371cd9f6642cbb9e9a677f445de3530affected · git
    • 5.10.260 and later · before 5.10.273affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:12linux-6.12before 6.12.113-1~deb12u16.12.113-1~deb12u1
Debian:13linuxbefore 6.12.113-16.12.113-1
Debian:14linuxbefore 7.2.10-17.2.10-1

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-2026-98838Oct 18, 2026 · vt: skip screen update for DEC alignment test on backgroup consoles
    0Monitor
  • ← EarlierCVE-2026-98839Oct 18, 2026 · vt: selection: Fix unsigned underflow and slab-out-of-bounds read in paste_selection()
    0Monitor
  • Later →CVE-2026-98841Oct 18, 2026 · virt: vmgenid: set driver_data before registering notification handlers
    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 Linux1485a3dd97ab1af2605243cabe6b604546d46dd1Vendor (CNA)
Linux Linux226bd5603371cd9f6642cbb9e9a677f445de3530Vendor (CNA)
Linux Linux233a2e190b12884d186027d0b86d43a48799b69cVendor (CNA)
Linux Linux5.10.273Vendor (CNA)
Linux Linux5.15.224Vendor (CNA)
Linux Linux6.1.191Vendor (CNA)
Linux Linux6.12.113Vendor (CNA)
Linux Linux6.18.56Vendor (CNA)
Linux Linux6.6.160Vendor (CNA)
Linux Linux7.1Vendor (CNA)
Linux Linux7.2Vendor (CNA)
Linux Linux942742000a0288d4ca60c448894aabacd48004d5Vendor (CNA)
Linux Linux9dfcadc5e003fb250dd471db90144bd5366140e9Vendor (CNA)
Linux Linuxc073d01f6f5367c3a4f07efd507274ed0d03acd0Vendor (CNA)
Linux Linuxc9f56d4b29792a62b17f2051ba93fd3b40a479ecVendor (CNA)
Linux Linuxcbc05413d3694193494b2374b56bae801ac41fecVendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.159.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.12.113-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.113-1~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.

  1. Published
  2. Fix recordedsame day
  3. TodayNov 6, 2026+19 d
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.

—

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. Exploit maturity— → none
  2. 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