CVE-2026-43190: netfilter: xt_tcpmss: check remaining length before reading optlen
Vulnerability summary
CVE-2026-43190 is a high (CVSS 8.2) Out-of-bounds Read vulnerability in linux. EPSS estimates a 0.46% chance of exploitation in the next 30 days, higher than 40.1% of scored vulnerabilities.
Severe, CVSS 8.2 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 0% (FIRST, 03-11-2026)
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 168 · Related 154Showing 100 of 168.
Timeline
- 06-05-2026PublishedVulnerability first disclosed.
- 19-10-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_tcpmss: check remaining length before reading optlen Quoting reporter: In net/netfilter/xt_tcpmss.c (lines 53-68), the TCP option parser reads op[i+1] directly without validating the remaining option length. If the last byte of the option field is not EOL/NOP (0/1), the code attempts to index op[i+1]. In the case where i + 1 == optlen, this causes an out-of-bounds read, accessing memory past the optlen boundary (either reading beyond the stack buffer _opt or the following payload).
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated8.2HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
- OSV · DebianEcosystem advisory · calculated8.2HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
- NVDNIST8.2HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
EPSS trend
Probability
0.46%
Chance of exploitation in the next 30 days
Percentile
40%
Versus all other CVEs
30-day change
Decrease -0.17 pp
From 0.63% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu157 products
- linuxAll versions (No fix recorded) | < 5.15.0-186.196 | < 6.8.0-134.134
- linux-allwinner-5.19All versions (No fix recorded)
- linux-awsAll versions (No fix recorded) | < 5.15.0-1112.119 | < 6.8.0-1060.63
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < f895191dc32c53eaf443b6443fe40945b2f92287 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < cd5beda7e0e32865e214f28034bb92c1cecff885 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < eaedc0bc18be46fe7f58170e967959a932c4f824 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 07a9b32eaae792ff7d0fcac14d8920c937c0a9c3 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 8b300f726640c48c3edfe9c453334dd801f4b74e | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 5e13d0a37666955b6cfddc0f73cb40ed645b8a05 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < f6c412dcfd76b0516d51aa847d8f4c7b70381b09 | ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 735ee8582da3d239eb0c7a53adca61b79fb228b3 | 2.6.12
- linux_kernel≥ 2.6.12.1, < 5.10.252 | ≥ 5.11, < 5.15.202 | ≥ 5.16, < 6.1.165 | ≥ 6.2, < 6.6.128 | ≥ 6.7, < 6.12.75 | ≥ 6.13, < 6.18.16 | ≥ 6.19, < 6.19.6 | 2.6.12 | 2.6.12:rc2 | 2.6.12:rc3 | 2.6.12:rc4 | 2.6.12:rc5 | 2.6.12:rc6
Debian1 product
- linux< 6.1.170-1 | < 6.12.85-1 | < 6.19.6-1
3 vendors · 160 products
