CVE-2021-47515

mediumpriority · track · 22EPSS 0.007 · 55 %ileDEEURUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.75% (55th) EPSS

CVSS 5.5 · medium

Is it mine?

59 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

In the Linux kernel, the following vulnerability has been resolved: seg6: fix the iif in the IPv6 socket control block When an IPv4 packet is received, the ip_rcv_core(...) sets the receiving interface index into the IPv4 socket control block (v5.16-rc4, net/ipv4/ip_input.c line 510): IPCB(skb)->iif = skb->skb_iif; If that IPv4 packet is meant to be encapsulated in an outer IPv6+SRH header, the seg6_do_srh_encap(...) performs the required encapsulation. In this case, the seg6_do_srh_encap function clears the IPv6 socket control block (v5.16-rc4 net/ipv6/seg6_iptunnel.c line 163): memset(IP6CB(skb), 0, sizeof(*IP6CB(skb))); The memset(...) was introduced in commit ef489749aae5 ("ipv6: sr: clear IP6CB(skb) on SRH ip4ip6 encapsulation") a long time ago (2019-01-29). Since the IPv6 socket control block and the IPv4 socket control block share the same memory area (skb->cb), the receiving interface index info is lost (IP6CB(skb)->iif is set to zero). As a side effect, that condition triggers a NULL pointer dereference if commit 0857d6f8c759 ("ipv6: When forwarding count rx stats on the orig netdev") is applied. To fix that issue, we set the IP6CB(skb)->iif with the index of the receiving interface once again.

cvss

Technical severity, 0–10. One row per scoring source.

7.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 5.1–7.5

v3.15.5mediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 1.8 · impact 3.6

v3.15.5mediumAV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hsecondary · FSTEC (BDU) RU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · ENISA EU

v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondaryexploitability 3.9 · impact 3.6

v3.15.1mediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-476USprimaryCWE-476US

affected products (59)

Products and version ranges known to be affected.

Broadcom Brocade SANnavall versionscert_bundDEcpe:/a:broadcom:brocade_sannav:-
Debian Linuxall versionscert_bundDEcpe:/o:debian:debian_linux:-
Dell Avamarall versionscert_bundDEcpe:/a:dell:avamar:-
Dell NetWorkerall versionscert_bundDEcpe:/a:dell:networker:-
Dell NetWorker Virtual Editionall versionscert_bundDEcpe:/a:dell:networker:virtual_edition
Dell PowerProtect Data Domainall versionscert_bundDEcpe:/a:dell:powerprotect_data_domain:-
Dell PowerProtect Data Domain Management Centerall versionscert_bundDEcpe:/a:dell:powerprotect_data_domain_management_center:-
Dell PowerProtect Data Domain OSall versionscert_bundDEcpe:/o:dell:powerprotect_data_domain_os:-
EMC Avamarall versionscert_bundDEcpe:/a:emc:avamar:-
IBM InfoSphere Guardiumall versionscert_bundDEcpe:/a:ibm:infosphere_guardium:-
IBM QRadar SIEM <7.5.0 UP10 IF01all versionscert_bundDE
IBM Spectrum Protect Plus 10.1all versionscert_bundDEcpe:/a:ibm:spectrum_protect_plus:10.1
Open Source Linux Kernelall versionscert_bundDEcpe:/o:linux:linux_kernel:-
Oracle Linuxall versionscert_bundDEcpe:/o:oracle:linux:-
RESF Rocky Linuxall versionscert_bundDEcpe:/o:resf:rocky_linux:-
Red Hat Enterprise Linuxall versionscert_bundDEcpe:/o:redhat:enterprise_linux:-
SUSE Linuxall versionscert_bundDEcpe:/o:suse:suse_linux:-
Ubuntu Linuxall versionscert_bundDEcpe:/o:canonical:ubuntu_linux:-
IBM QRadar SIEM< 7.5.0 UP10 IF01cert_bundDE
Linux Linuxall versionsenisa_euvdEU

showing 20 of 59

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2024-1235Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of Service und unspezifische AngriffeDeutsch2024-05-26csaf · cert_bundDE
Ein lokaler Angreifer kann mehrere Schwachstellen im Linux-Kernel ausnutzen, um einen Denial-of-Service-Zustand zu erzeugen oder unspezifische Angriffe durchzuführen.

also known as (3)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd fstec_bdu cert_bund NVD CVE.org MITRE

published 2024-05-24modified 2026-08-04

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+8782 more

references (20)

External citations — patches, advisories, analysis.

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