7.8

CVE-2025-37890: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc

Modified
AliasesUBUNTU-CVE-2025-37890DEBIAN-CVE-2025-37890
Published 16-05-2025Last modified 05-08-2026

Vulnerability summary

CVE-2025-37890 is a high (CVSS 7.8) Use After Free vulnerability in debian debian_linux. EPSS estimates a 0.22% chance of exploitation in the next 30 days, higher than 12.9% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.22%
0%100%
Low · +0.01 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 131 · Related 107
DLA-4271-1DLA-4327-1DSA-5925-1MGASA-2025-0182MGASA-2025-0183RHSA-2025:12209

Showing 100 of 131.

Timeline

  1. 16-05-2025
    PublishedVulnerability first disclosed.
  2. 05-08-2026
    Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: net_sched: hfsc: Fix a UAF vulnerability in class with netem as child qdisc As described in Gerrard's report [1], we have a UAF case when an hfsc class has a netem child qdisc. The crux of the issue is that hfsc is assuming that checking for cl->qdisc->q.qlen == 0 guarantees that it hasn't inserted the class in the vttree or eltree (which is not true for the netem duplicate case). This patch checks the n_active class variable to make sure that the code won't insert the class in the vttree or eltree twice, catering for the reentrant case. [1] https://lore.kernel.org/netdev/CAHcdcOm+03OD2j6R0=YHKqmy=VgJ8xEOKuP6c7mSgnp-TEJJbw@mail.gmail.com/

CVSS metrics

5 scores · 4 sources · 2 versions

EPSS trend

Probability

0.22%

Chance of exploitation in the next 30 days

Percentile

13%

Versus all other CVEs

30-day change

Increase +0.01 pp

From 0.21% 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

Affected systems

Version check

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

Ubuntu138 products
  • linux< 5.4.0-219.239 | < 5.15.0-143.153 | < 6.8.0-63.66
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws< 5.4.0-1148.158 | < 5.15.0-1087.94 | < 6.8.0-1031.33
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
Debian2 products
Linux2 products
  • linux≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 273bbcfa53541cde38b2003ad88a59b770306421 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < e0cf8ee23e1915431f262a7b2dee0c7a7d699af0 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < e3e949a39a91d1f829a4890e7dfe9417ac72e4d0 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 8df7d37d626430035b413b97cee18396b3450bef | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 6082a87af4c52f58150d40dec1716011d871ac21 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 2e7093c7a8aba5d4f8809f271488e5babe75e202 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < ac39fd4a757584d78ed062d4f6fd913f83bd98b5 | ≥ 37d9cf1a3ce35de3df6f7d209bfb1f50cf188cea, < 141d34391abbb315d68556b7c67ad97885407547 | 5.0
  • linux_kernel≥ 5.0.1, < 5.4.294 | ≥ 5.5, < 5.10.238 | ≥ 5.11, < 5.15.182 | ≥ 5.16, < 6.1.138 | ≥ 6.2, < 6.6.90 | ≥ 6.7, < 6.12.28 | ≥ 6.13, < 6.14.6 | 5.0 | 5.0:rc3 | 5.0:rc4 | 5.0:rc5 | 5.0:rc6 | 5.0:rc7 | 5.0:rc8 | 6.15:rc1 | 6.15:rc2 | 6.15:rc3 | 6.15:rc4

3 vendors · 142 products

References

45 links
Show all 45 references