Linux KernelOperating system · Linux

CVE-2026-45933

HIGH · 7.8 CVSS v3.1 Published 2026-05-27

Fix available

A fix is available. Upgrade to 6.12.75 / 6.18.14 or later.

See remediation →

80/100

Remediation priority · High

Zero-click Patch available

Official description

NVD · unedited

In the Linux kernel, the following vulnerability has been resolved: bpf: Preserve id of register in sync_linked_regs() sync_linked_regs() copies the id of known_reg to reg when propagating bounds of known_reg to reg using the off of known_reg, but when known_reg was linked to reg like: known_reg = reg ; both known_reg and reg get same id known_reg += 4 ; known_reg gets off = 4, and its id gets BPF_ADD_CONST now when a call to sync_linked_regs() happens, let's say with the following: if known_reg >= 10 goto pc+2 known_reg's new bounds are propagated to reg but now reg gets BPF_ADD_CONST from the copy. This means if another link to reg is created like: another_reg = reg ; another_reg should get the id of reg but assign_scalar_id_before_mov() sees BPF_ADD_CONST on reg and assigns a new id to it. As reg has a new id now, known_reg's link to reg is broken. If we find new bounds for known_reg, they will not be propagated to reg. This can be seen in the selftest added in the next commit: 0: (85) call bpf_get_prandom_u32#7 ; R0=scalar() 1: (57) r0 &= 255 ; R0=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) 2: (bf) r1 = r0 ; R0=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) R1=scalar(id=1,smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) 3: (07) r1 += 4 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=4,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff)) 4: (a5) if r1 < 0xa goto pc+4 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=10,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff)) 5: (bf) r2 = r0 ; R0=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=255) R2=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=255) 6: (a5) if r1 < 0xe goto pc+2 ; R1=scalar(id=1+4,smin=umin=smin32=umin32=14,smax=umax=smax32=umax32=259,var_off=(0x0; 0x1ff)) 7: (35) if r0 >= 0xa goto pc+1 ; R0=scalar(id=2,smin=umin=smin32=umin32=6,smax=umax=smax32=umax32=9,var_off=(0x0; 0xf)) 8: (37) r0 /= 0 div by zero When 4 is verified, r1's bounds are propagated to r0 but r0 also gets BPF_ADD_CONST (bug). When 5 is verified, r0 gets a new id (2) and its link with r1 is broken. After 6 we know r1 has bounds [14, 259] and therefore r0 should have bounds [10, 255], therefore the branch at 7 is always taken. But because r0's id was changed to 2, r1's new bounds are not propagated to r0. The verifier still thinks r0 has bounds [6, 255] before 7 and execution can reach div by zero. Fix this by preserving id in sync_linked_regs() like off and subreg_def.

Technical summary

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions

NVD · CPE data

Linux KernelOperating system

Affected:>= 6.11, < 6.12.75>= 6.13, < 6.18.14>= 6.19, < 6.19.4

CVSS breakdown

From the vector

Attack vector: Local
Complexity: Low
Privileges: Low
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Remediation

dbcve · scoped

Upgrade available Upgrade to 6.12.75 / 6.18.14 / 6.19.4 or later

Fixed in 6.12.756.18.146.19.4

Vendor patch git.kernel.org →

Recommended fix High confidence

6.12.75 (for 6.11-6.12 branches), 6.18.14 (for 6.13-6.17 branches), or 6.19.4 (for 6.19 branch)

Identify the current kernel version using 'uname -r'
Determine which kernel branch you are on (6.11.x, 6.12.x, 6.13-6.17.x, or 6.19.x)
If on kernel 6.11.x or 6.12.x, upgrade to kernel version 6.12.75 or later
If on kernel 6.13.x through 6.17.x, upgrade to kernel version 6.18.14 or later
If on kernel 6.19.x, upgrade to kernel version 6.19.4 or later
Reboot the system to load the new kernel
Verify the fix is applied by checking the kernel version and confirming the BPF verifier behavior is corrected

Caveat Standard kernel upgrade risks apply - ensure compatibility with existing modules and software before deploying

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,950. Get the upgrade done

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References

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-45933 in production — separate from our analysis above.

Notes0 Guidelines

Know something about CVE-2026-45933?

The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.

The version that genuinely resolved it — not the one the vendor claimed
A config change or rule that shut the vector down
A gotcha in the upgrade path that cost you an afternoon

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here

Verified mitigations, workarounds, and config changes
Version or environment caveats, and links to real fixes
No weaponised exploit code, or anything meant to cause harm
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At a glance

A fix existsUpgrade to 6.12.75 / 6.18.14 or later

Severity 7.8 High

Exploit likelihood EPSS, next 30 days 0.2%

Affects: Linux Kernel

Remediation

A high-priority fix

Get a fix

Estimated effortfrom ~11 hrs

ComplexityModerate

Typical engagementfrom $1,950

What a fix involves

We scope it with you and confirm a fixed quote
A specialist builds a reviewed fix
You deploy it to staging first
Optional re-test once it’s live

A high-priority vulnerability. Send your environment and a specialist will scope CVE-2026-45933 and return a fixed quote and timeline.

You’ll deal with our team directly and deploy the reviewed fix to staging first — never straight to production.

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

Scan for this in your stack

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Practitioner notes

No notes yet

Official description

Technical summary

Affected products & versions

CVSS breakdown

Remediation

References