CVE-2026-43038: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()
Noroxi assessment
Priority: Monitor (action score 39/100)
- 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: 0.25% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: Linux Linux 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7, 1ceeebd5bd6d855b17a5df625109bfe29129d7cf, 3d5127d998de617b130aae96b138dba22ac6a8a7.
- Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Low priority for now. Upgrade to Linux Linux 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7, 1ceeebd5bd6d855b17a5df625109bfe29129d7cf, 3d5127d998de617b130aae96b138dba22ac6a8a7 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: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway.
- BDU:2026-08754
- ALSA-2026:25120
- ALSA-2026:25121
- ALSA-2026:30129
- ALSA-2026:30848
- RHSA-2026:22900
- RHSA-2026:22940
- RHSA-2026:22964
- RHSA-2026:23224
- RHSA-2026:23237
- RHSA-2026:24343
- RHSA-2026:25120
- RHSA-2026:25121
- RHSA-2026:25533
- RHSA-2026:26535
- RHSA-2026:30129
- RHSA-2026:30848
- RHSA-2026:55618
- RHSA-2026:55761
- RHSA-2026:55762
- Published
- May 1, 2026
- Updated
- Oct 19, 2026
- EPSS
- 0.2% · 17th percentile
- CWE
- CWE-787
Report tools
Action score
39
Monitor
Low priority for now.
- CVSS
- 39 / 40 · 9.8 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · Linux
- 9.8
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected 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.
| Vendor | Product | CPE |
|---|---|---|
| linux | linux kernel | cpe:2.3:o:linux:linux_kernel |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- linux linux kernelafter 3.13 · before 5.10.253
- linux linux kernel5.11 and later · before 5.15.203
- linux linux kernel5.16 and later · before 6.1.168
- linux linux kernel6.2 and later · before 6.6.134
- linux linux kernel6.7 and later · before 6.12.81
- linux linux kernel6.13 and later · before 6.18.22
- linux linux kernel6.19 and later · before 6.19.12
- linux linux kernel3.13
- linux linux kernel7.0
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
- 3.13affected
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before c438ba010171b70bad22fc18b1d5bdc3627476e8affected · git
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7affected · git
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before a4437faf135da293d16fcc4cc607316742bd0ebbaffected · git
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before 3d5127d998de617b130aae96b138dba22ac6a8a7affected · git
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before e41953e7d118e2702bcb217879c173d9d1d3cd4eaffected · git
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before a2edbb6393972a02114b6003953a5cef3104fadaaffected · git
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before 1ceeebd5bd6d855b17a5df625109bfe29129d7cfaffected · git
- ca15a078bd907df5fc1c009477869c5cbde3b753 and later · before 86ab3e55673a7a49a841838776f1ab18d23a67b5affected · git
- before 3.13not affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:10 | kernel | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-core | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-debug | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-debug-core | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-debug-devel | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-debug-devel-matched | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-debug-modules | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-debug-modules-core | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-debug-modules-extra | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-devel | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-devel-matched | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-modules | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-modules-core | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-64k-modules-extra | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-abi-stablelists | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-core | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-cross-headers | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-debug | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-debug-core | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-debug-devel | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-debug-devel-matched | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-debug-modules | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
| AlmaLinux:10 | kernel-debug-modules-core | before 6.12.0-211.28.1.el10_2 | 6.12.0-211.28.1.el10_2 |
+96
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV90Now
- CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV89Now
- CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV85Now
Published before and after this one in the same product
- ← EarlierCVE-2026-43036May 1, 2026 · net: use skb_header_pointer() for TCPv4 GSO frag_off check22Monitor
- ← EarlierCVE-2026-43037May 1, 2026 · ip6_tunnel: clear skb2->cb[] in ip4ip6_err()39Monitor
- Later →CVE-2026-43040May 1, 2026 · net: ipv6: ndisc: fix ndisc_ra_useropt to initialize nduseropt_padX fields to zero to prevent an info-leak28Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7 | Vendor (CNA) |
| Linux Linux | 1ceeebd5bd6d855b17a5df625109bfe29129d7cf | Vendor (CNA) |
| Linux Linux | 3d5127d998de617b130aae96b138dba22ac6a8a7 | Vendor (CNA) |
| Linux Linux | 86ab3e55673a7a49a841838776f1ab18d23a67b5 | Vendor (CNA) |
| Linux Linux | a2edbb6393972a02114b6003953a5cef3104fada | Vendor (CNA) |
| Linux Linux | a4437faf135da293d16fcc4cc607316742bd0ebb | Vendor (CNA) |
| Linux Linux | c438ba010171b70bad22fc18b1d5bdc3627476e8 | Vendor (CNA) |
| Linux Linux | e41953e7d118e2702bcb217879c173d9d1d3cd4e | Vendor (CNA) |
| almalinux:bpftool | 4.18.0-553.132.1.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel | 4.18.0-553.132.1.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-core | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-core | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-devel | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-modules | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-debug-modules-extra | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-devel | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-modules | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:kernel-rt-modules-extra | 4.18.0-553.132.1.rt7.473.el8_10 · AlmaLinux:8 | Package registry (OSV) |
| debian:linux | 6.1.170-1 · Debian:12 | Package registry (OSV) |
| red hat:kernel-rt | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-core | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-core | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-debuginfo | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-devel | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-kvm | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-modules | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
| red hat:kernel-rt-debug-modules-core | 0:5.14.0-284.174.1.rt14.459.el9_2 · Red Hat:rhel_e4s:9.2::nfv | Package registry (OSV) |
+17
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.
No history yet (it accumulates with the daily EPSS job).
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 researchersFinders, 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).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-26-0143 · May 4, 2026(Linux Kernel Güvenlik Bildirimi)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-787 · Out-of-bounds WriteCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
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
- SSVC exploitation— → none
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (19 more)Show less
- git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7
- git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf
- git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7
- git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5
- git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada
- git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb
- git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8
- git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e
- access.redhat.com/errata/RHSA-2026:22900
- access.redhat.com/errata/RHSA-2026:22940
- access.redhat.com/errata/RHSA-2026:22964
- access.redhat.com/errata/RHSA-2026:23224
- access.redhat.com/errata/RHSA-2026:23237
- access.redhat.com/errata/RHSA-2026:24343
- access.redhat.com/errata/RHSA-2026:25120
- access.redhat.com/errata/RHSA-2026:25121
- access.redhat.com/errata/RHSA-2026:25533
- access.redhat.com/errata/RHSA-2026:26535
- access.redhat.com/errata/RHSA-2026:30129
Vendor advisories and official records. Exploit/PoC links are deliberately left out.