5.5

CVE-2026-23254: net: gro: fix outer network offset

Analyzed
AliasesUBUNTU-CVE-2026-23254DEBIAN-CVE-2026-23254
Published 18-03-2026Last modified 23-05-2026

Vulnerability summary

CVE-2026-23254 is a medium (CVSS 5.5) vulnerability in linux. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.7% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 5.5, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
5.5/10
010
Medium · v3.1 (NVD)
EPSS score
0.12%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 16 · Related 14
MGASA-2026-0097MGASA-2026-0098OPENSUSE-SU-2026:20965-1SUSE-SU-2026:22099-1SUSE-SU-2026:22112-1SUSE-SU-2026:22117-1

Timeline

  1. 18-03-2026
    PublishedVulnerability first disclosed.
  2. 23-05-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: net: gro: fix outer network offset The udp GRO complete stage assumes that all the packets inserted the RX have the `encapsulation` flag zeroed. Such assumption is not true, as a few H/W NICs can set such flag when H/W offloading the checksum for an UDP encapsulated traffic, the tun driver can inject GSO packets with UDP encapsulation and the problematic layout can also be created via a veth based setup. Due to the above, in the problematic scenarios, udp4_gro_complete() uses the wrong network offset (inner instead of outer) to compute the outer UDP header pseudo checksum, leading to csum validation errors later on in packet processing. Address the issue always clearing the encapsulation flag at GRO completion time. Such flag will be set again as needed for encapsulated packets by udp_gro_complete().

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.12%

Chance of exploitation in the next 30 days

Percentile

2%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.11% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

No weakness data has been published for this record.

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu130 products
  • linux< 6.8.0-117.117 | All versions (No fix recorded)
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 6.8.0-1055.58 | All versions (No fix recorded)
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Linux2 products
  • linux≥ af276a5ac8e938c8b058e3e124073cc1e322d98b, < 9d40a85138568696387ef04cd004c64612a70874 | ≥ 5ef31ea5d053a8f493a772ebad3f3ce82c35d845, < b83557bc6f560433fe5d727e241069f8db5ba709 | ≥ 5ef31ea5d053a8f493a772ebad3f3ce82c35d845, < 2e5edb69e5d0e23ef248c56fc977039268c77a7b | ≥ 5ef31ea5d053a8f493a772ebad3f3ce82c35d845, < 5c2c3c38be396257a6a2e55bd601a12bb9781507 | dbd9466d323a72e22efe09151253d195d36d3bf6 | ≥ 6.6.31, < 6.6.124 | ≥ 6.8.10, < 6.9 | 6.9
  • linux_kernelEOL≥ 6.6.31, < 6.6.124 | ≥ 6.8.10, < 6.9 | ≥ 6.9.1, < 6.12.70 | ≥ 6.13, < 6.18.10 | 6.9 | 6.9:rc7 | 6.19:rc1 | 6.19:rc2 | 6.19:rc3 | 6.19:rc4 | 6.19:rc5 | 6.19:rc6 | 6.19:rc7 | 6.19:rc8
Debian1 product
  • linux< 6.12.73-1 | < 6.18.10-1

3 vendors · 133 products

References

17 links
Show all 17 references