CVE-2025-39770

mediumpriority · track · 22EPSS 0.004 · 31 %ileDEEUFRNLRUUS
grimoire priorityP3 · Track
Exploitable?
—
no known exploitation
Likely / severe?
0.38% (31st) EPSS
CVSS 5.5 · medium
Is it mine?
140 products
Check your exposure
Who says so?
8 sources
cnnvd · enisa_euvd · fstec_bdu · cert_bund

EPSS · scored 2026-10-27

In the Linux kernel, the following vulnerability has been resolved: net: gso: Forbid IPv6 TSO with extensions on devices with only IPV6_CSUM When performing Generic Segmentation Offload (GSO) on an IPv6 packet that contains extension headers, the kernel incorrectly requests checksum offload if the egress device only advertises NETIF_F_IPV6_CSUM feature, which has a strict contract: it supports checksum offload only for plain TCP or UDP over IPv6 and explicitly does not support packets with extension headers. The current GSO logic violates this contract by failing to disable the feature for packets with extension headers, such as those used in GREoIPv6 tunnels. This violation results in the device being asked to perform an operation it cannot support, leading to a `skb_warn_bad_offload` warning and a collapse of network throughput. While device TSO/USO is correctly bypassed in favor of software GSO for these packets, the GSO stack must be explicitly told not to request checksum offload. Mask NETIF_F_IPV6_CSUM, NETIF_F_TSO6 and NETIF_F_GSO_UDP_L4 in gso_features_check if the IPv6 header contains extension headers to compute checksum in software. The exception is a BIG TCP extension, which, as stated in commit 68e068cabd2c6c53 ("net: reenable NETIF_F_IPV6_CSUM offload for BIG TCP packets"): "The feature is only enabled on devices that support BIG TCP TSO. The header is only present for PF_PACKET taps like tcpdump, and not transmitted by physical devices." kernel log output (truncated): WARNING: CPU: 1 PID: 5273 at net/core/dev.c:3535 skb_warn_bad_offload+0x81/0x140 ... Call Trace: <TASK> skb_checksum_help+0x12a/0x1f0 validate_xmit_skb+0x1a3/0x2d0 validate_xmit_skb_list+0x4f/0x80 sch_direct_xmit+0x1a2/0x380 __dev_xmit_skb+0x242/0x670 __dev_queue_xmit+0x3fc/0x7f0 ip6_finish_output2+0x25e/0x5d0 ip6_finish_output+0x1fc/0x3f0 ip6_tnl_xmit+0x608/0xc00 [ip6_tunnel] ip6gre_tunnel_xmit+0x1c0/0x390 [ip6_gre] dev_hard_start_xmit+0x63/0x1c0 __dev_queue_xmit+0x6d0/0x7f0 ip6_finish_output2+0x214/0x5d0 ip6_finish_output+0x1fc/0x3f0 ip6_xmit+0x2ca/0x6f0 ip6_finish_output+0x1fc/0x3f0 ip6_xmit+0x2ca/0x6f0 inet6_csk_xmit+0xeb/0x150 __tcp_transmit_skb+0x555/0xa80 tcp_write_xmit+0x32a/0xe90 tcp_sendmsg_locked+0x437/0x1110 tcp_sendmsg+0x2f/0x50 ... skb linear: 00000000: e4 3d 1a 7d ec 30 e4 3d 1a 7e 5d 90 86 dd 60 0e skb linear: 00000010: 00 0a 1b 34 3c 40 20 11 00 00 00 00 00 00 00 00 skb linear: 00000020: 00 00 00 00 00 12 20 11 00 00 00 00 00 00 00 00 skb linear: 00000030: 00 00 00 00 00 11 2f 00 04 01 04 01 01 00 00 00 skb linear: 00000040: 86 dd 60 0e 00 0a 1b 00 06 40 20 23 00 00 00 00 skb linear: 00000050: 00 00 00 00 00 00 00 00 00 12 20 23 00 00 00 00 skb linear: 00000060: 00 00 00 00 00 00 00 00 00 11 bf 96 14 51 13 f9 skb linear: 00000070: ae 27 a0 a8 2b e3 80 18 00 40 5b 6f 00 00 01 01 skb linear: 00000080: 08 0a 42 d4 50 d5 4b 70 f8 1a

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedSIMATIC CN 4100siemens_psirt

    Update to V5.0 or later version

    https://support.industry.siemens.com/cs/ww/en/view/109814144/
  • FixedSIMATIC CN 4100cisa_csaf_ot

    Update to V5.0 or later version

    https://support.industry.siemens.com/cs/ww/en/view/109814144/
  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)siemens_psirt

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • MitigationSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot

    Limit access to the interactive shell of the additional GNU/Linux subssytem to trusted personnel only.

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)siemens_psirt

    Currently no fix is available

  • No fix availableSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)siemens_psirt

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0)cisa_csaf_ot

    Currently no fix is available

  • No fix availableSIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0)cisa_csaf_ot

    Currently no fix is available

02

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
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · CISA US
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
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · Siemens ProductCERT DE
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)
v3.17highCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:Hsecondary · NCSC-NL NL
03

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-573USCWE-573USCWE-573USCWE-841US
04

affected products (140)

Products and version ranges known to be affected.

showing 20 of 140
05

advisories (11)

Vendor and ecosystem advisories describing this.

  • NCSC-2026-0147Kwetsbaarheden verholpen in Siemens-productenNL2026-05-13csaf · ncsc_nlNL

    Siemens heeft kwetsbaarheden verholpen in verschillende (OT-)producten. Het gaat onder andere om producten in de Siemens RUGGEDCOM-, SCALANCE-, SIMATIC-, SIMIT-, SINAMICS-, SIPROTEC-, SENTRON- en Solid Edge-productreeksen.

  • SSA-019113SSA-019113: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.62026-07-14csaf · siemens_psirtDE

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.6 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fix versions and recommends specific countermeasures for products where fixes are not, or not yet available. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.6 is no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V3.1.6 only; for version V3.1.7 refer to SSA-457936.

  • SSA-032379SSA-032379: Multiple Vulnerabilities in SIMATIC CN 4100 Before V5.02026-05-12csaf · siemens_psirtDE

    SIMATIC CN 4100 contains multiple vulnerabilities which could potentially lead to a compromise in availability, integrity and confidentiality. Siemens has released a new version for SIMATIC CN 4100 and recommends to update to the latest version.

  • SSA-082556SSA-082556: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.52025-06-10csaf · siemens_psirtDE

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens has released new versions for several affected products and recommends to update to the latest versions. Siemens is preparing further fixes and recommends specific mitigations for products where fixes are not or not yet available. SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.5 is no longer maintained and there won't be any update to the CVE list anymore. Please update to the latest version. Note: This SSA advises vulnerabilities for firmware version V3.1.5 only; for version V3.1.6 refer to SSA-019113.

  • SSA-457936SSA-457936: Vulnerabilities in the additional GNU/Linux subsystem of the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP V3.1.72026-10-13csaf · siemens_psirtDE

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.7 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.

  • WID-SEC-W-2025-2040Linux Kernel: Mehrere Schwachstellen ermöglichen Denial of ServiceDeutsch2025-09-11csaf · cert_bundDE

    Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Linux Kernel ausnutzen, um Sicherheitsmechanismen zu umgehen, sowie einen Denial of Service Angriff oder andere nicht spezifizierte Angriffe durchzuführen.

  • ICSA-25-162-05Siemens SIMATIC S7-1500 CPU family2025-06-10icsa · cisa_csaf_otUS

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.5 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fix versions and recommends countermeasures for products where fixes are not, or not yet available.

  • ICSA-26-134-10Siemens SIMATIC2026-05-12icsa · cisa_csaf_otUS

    SIMATIC CN 4100 contains multiple vulnerabilities which could potentially lead to a compromise in availability, integrity and confidentiality. Siemens has released a new version for SIMATIC CN 4100 and recommends to update to the latest version.

  • ICSA-26-209-04Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP2026-07-14icsa · cisa_csaf_otUS

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.6 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fix versions and recommends specific countermeasures for products where fixes are not, or not yet available.

  • ICSA-26-295-11Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP2026-10-13icsa · cisa_csaf_otUS

    Multiple vulnerabilities have been identified in the additional GNU/Linux subsystem of the firmware version V3.1.7 for the SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP (incl. SIPLUS variant). Siemens is preparing fixes and recommends specific mitigations for products where fixes are not or not yet available.

  • CERTFR-2026-AVI-1298Multiples vulnérabilités dans les produits SiemensFrançais2026-10-13vendor · certfrFR
06

also known as (4)

Other names and identifiers for this entity.

07

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducert_bundncsc_nlsiemens_psirtcisa_csaf_otcertfrNVDCVE.orgMITRE
published 2025-09-11modified 2026-10-19
08

references (22)

External citations — patches, advisories, analysis.

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