CVE-2026-43501Known exploitationPublic exploitNetwork attack vector

Root shell via RPL SRH headroom underflow

Published May 21, 2026 · Updated May 21, 2026

Out-of-bounds write in Linux Kernel 5.7 through 7.1-rc1 allows remote attackers to gain a root shell via a crafted IPv6 RPL SRH. ipv6_rpl_srh_rcv() recompresses an intermediate source-routing header without ensuring space for mac_len, so a wrapped u16 MAC offset makes memmove() overwrite 14 bytes about 64 KiB past the packet buffer. Remote reachability requires rpl_seg_enabled, while local users can reach the path through enabled unprivileged user and network namespaces; the published exploit gains arbitrary kernel read/write and root execution.

CVSS severity9.8
Critical
EPSS probability0.63%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in Linux Kernel 5.7 through 7.1-rc1 allows remote attackers to gain a root shell via a crafted IPv6 RPL SRH. ipv6_rpl_srh_rcv() recompresses an intermediate source-routing header without ensuring space for mac_len, so a wrapped u16 MAC offset makes memmove() overwrite 14 bytes about 64 KiB past the packet buffer. Remote reachability requires rpl_seg_enabled, while local users can reach the path through enabled unprivileged user and network namespaces; the published exploit gains arbitrary kernel read/write and root execution.

The record

CVE
CVE-2026-43501
Published
May 21, 2026
Updated
May 21, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-787, CWE-131, T1068
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 22, 2026Exploitation reportedSuccessful kernelCTF exploit chain
  2. May 21, 2026CVE publishedPublication date reported by the CVE source.
  3. May 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=5.7
  2. Affected versionversion=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <4babc2d9fda2df43823b85d08a0180b68f1b0854
  3. Affected versionversion=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <7398ebefbfd4f8a31d4f665a4213302fa995494b
  4. Affected versionversion=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <8e8be63465a5e80394c70324603dfea1bfdad48f
  5. Affected versionversion=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <9e6bf146b55999a095bb14f73a843942456d1adc
  6. Affected versionversion=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <c261d07a80576dc8ccf394ef8f074f8c67a06b37

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=5.7; version=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <4babc2d9fda2df43823b85d08a0180b68f1b0854; version=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <7398ebefbfd4f8a31d4f665a4213302fa995494b; version=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <8e8be63465a5e80394c70324603dfea1bfdad48f; version=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <9e6bf146b55999a095bb14f73a843942456d1adc; version=8610c7c6e3bd647ff98d21c8bc0580e77bc2f8b3 <c261d07a80576dc8ccf394ef8f074f8c67a06b37

Published CVSS scores

9.8Linux kernel CVE teamCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5Red HatCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-131Incorrect Calculation of Buffer Size
T1068Exploitation for Privilege Escalation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Reported exploitation

Technologies

Your stack

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Your stack

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