Answer in brief
CVE-2026-63992 records a Unknown severity vulnerability in tunnels: do not assume transport header in iptunnel_pmtud_check_icmp(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-63992 records a Unknown severity vulnerability in tunnels: do not assume transport header in iptunnel_pmtud_check_icmp(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <5a92cb45e34749865d03daf8d3500f77b5f6644c || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <c7b7ec3e69e673c0d6b57f74d21da50c485c598e || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <7f4f7efe7f30edd29c4988de01728bf2398217e4 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <a096b6e34f602950af9a2b0856cd93a5f4c276d7 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <43368636c663cff6e59dde93cf4b8e43ac28eb93 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <cb549df9ce4ee15c9d5b19ddab12cf2128e4313c || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <509323077ef79a26ba0c60bb556e45c12c398b2d | 5a92cb45e34749865d03daf8d3500f77b5f6644c, c7b7ec3e69e673c0d6b57f74d21da50c485c598e, 7f4f7efe7f30edd29c4988de01728bf2398217e4, e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec, a096b6e34f602950af9a2b0856cd93a5f4c276d7, 43368636c663cff6e59dde93cf4b8e43ac28eb93, cb549df9ce4ee15c9d5b19ddab12cf2128e4313c, 509323077ef79a26ba0c60bb556e45c12c398b2d |
| Linux/Linuxgeneric | 5.9 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: tunnels: do not assume transport header in iptunnel_pmtud_check_icmp() In some cases, iptunnel_pmtud_check_icmp() can be called while skb transport header is not set. This triggers an out-of-bound access, because (typeof(skb->transport_header))~0U is 65535. Access the icmp header based on IPv4 network header, after making sure icmp->type is present in skb linear part. Note that iptunnel_pmtud_check_icmpv6()) is fine.
Quoted source text, attributed separately from HOL analysis.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <5a92cb45e34749865d03daf8d3500f77b5f6644c || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <c7b7ec3e69e673c0d6b57f74d21da50c485c598e || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <7f4f7efe7f30edd29c4988de01728bf2398217e4 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <a096b6e34f602950af9a2b0856cd93a5f4c276d7 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <43368636c663cff6e59dde93cf4b8e43ac28eb93 || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <cb549df9ce4ee15c9d5b19ddab12cf2128e4313c || >=4cb47a8644cc9eb8ec81190a50e79e6530d0297f <509323077ef79a26ba0c60bb556e45c12c398b2d | 5a92cb45e34749865d03daf8d3500f77b5f6644c, c7b7ec3e69e673c0d6b57f74d21da50c485c598e, 7f4f7efe7f30edd29c4988de01728bf2398217e4, e917d0c69f01af2bb4fbea2b66d560a53b3ac7ec, a096b6e34f602950af9a2b0856cd93a5f4c276d7, 43368636c663cff6e59dde93cf4b8e43ac28eb93, cb549df9ce4ee15c9d5b19ddab12cf2128e4313c, 509323077ef79a26ba0c60bb556e45c12c398b2d |
| Linux/Linuxgeneric | 5.9 | Not reported |
Published upstream
Jul 19, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
In the Linux kernel, the following vulnerability has been resolved: tunnels: do not assume transport header in iptunnel_pmtud_check_icmp() In some cases, iptunnel_pmtud_check_icmp() can be called while skb transport header is not set. This triggers an out-of-bound access, because (typeof(skb->transport_header))~0U is 65535. Access the icmp header based on IPv4 network header, after making sure icmp->type is present in skb linear part. Note that iptunnel_pmtud_check_icmpv6()) is fine.
Quoted source text, attributed separately from HOL analysis.