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CVE-2026-27775

Gitea pre-receive hook permission cache allows full repository write access

8.8 HighFix available

Gitea 1.25.5 caches a branch-specific write-permission result across multiple refs in one pre-receive hook session, allowing a per-branch maintainer-edit grant to be reused for other refs and escalate to full repository write access.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.91%Up 0.7 points since Jul 4, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.8

Gitea pre-receive hook permission cache allows full repository write access

Gitea 1.25.5 caches a branch-specific write-permission result across multiple refs in one pre-receive hook session, allowing a per-branch maintainer-edit grant to be reused for other refs and escalate to full repository write access.

Record
CVE-2026-27775
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
EUVDEUVD-2026-41636 8.8

Gitea 1.25.5 caches a branch-specific write-permission result across multiple refs in one pre-receive hook session, allowing a per-branch maintainer-edit grant to be reused for other refs and escalate to full repository write access.

Record
EUVD-2026-41636
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-649p-mmhf-85c7 8.8

Gitea: Cached Per-Branch Permission Check in Pre-Receive Hook Allows Full Repository Write

Vulnerability Header

| Field | Value | | ------------------- | ----------------------------------------------------------------------------------- | | Vulnerability Title | Cached Per-Branch Permission Check in Pre-Receive Hook Allows Full Repository Write | | Severity Rating | High | | Bug Category | Authorization Bypass | | Location | routers/private/hook_pre_receive.go:55-64, CanWriteCode() | | Affected Versions | 1.25.5 |

Executive Summary

The pre-receive hook in Gitea evaluates the CanMaintainerWriteToBranch permission only once per git push session and caches the result for all subsequent refs in the same batch. An attacker who has a legitimate per-branch write grant (e.g., via an open pull request with "Allow edits from maintainers" enabled) can batch-push that branch together with any other ref. The cached true from the first ref is reused for all following refs, allowing the attacker to overwrite protected branches (including main), create arbitrary new branches, and push tags. This effectively escalates a single-branch maintainer-edit grant into full repository write access.

Root Cause Analysis

Technical Description

When processing a multi-ref git push, the HookPreReceive handler at hook_pre_receive.go:107 iterates over all incoming refs. For each branch ref, preReceiveBranch (:140) updates ctx.branchName to the current branch (:142) and then calls AssertCanWriteCode() (:144).

CanWriteCode() (:55-64) checks whether the user can write to the repository. On the first call, it evaluates issues_model.CanMaintainerWriteToBranch(ctx, userPerm, ctx.branchName, user) and stores the result in a boolean flag (canWriteCode) with a guard (checkedCanWriteCode). On all subsequent calls within the same batch, it returns the cached boolean without re-evaluating against the now-different ctx.branchName.

This means the permission check is branch-specific in its inputs but session-scoped in its caching — a classic check-vs-use divergence.

A second contributing factor is the AGit-flow relaxation at routers/web/repo/githttp.go:190-192 (and routers/private/serv.go:337-338), which downgrades the outer receive-pack access gate from Write to Read when git.DefaultFeatures().SupportProcReceive is true (git ≥ 2.29). This allows a user with only Read access on a repository to initiate a receive-pack session, deferring all authorization to the pre-receive hook — which contains the caching bug described above.

First Faulty Condition

| File | routers/private/hook_pre_receive.go | | --------- | ------------------------------------- | | Line | 55-64 | | Condition | CanWriteCode() evaluates the branch-specific CanMaintainerWriteToBranch check only on the first invocation and caches the result, reusing it for all subsequent refs in the batch regardless of which branch they target. |

Trace Analysis

The following is the path from the attacker's git push to the authorization fault:

  1. POST /{owner}/{repo}.git/git-receive-pack → routers/web/repo/githttp.go:437 (ServiceReceivePack) → httpBase() (:60)

    • Access gate is downgraded from Write to Read at :190-192 due to AGit-flow support.

  2. git receive-pack invokes the pre-receive hook → cmd/hook.go:184 (runHookPreReceive) → modules/private/hook.go:96 (HookPreReceive) → internal API → routers/private/hook_pre_receive.go:107 (HookPreReceive)

  3. Loop at :117 iterates over all refs in the batch. For each branch ref, preReceiveBranch (:140) sets ctx.branchName at…

Record
GHSA-649p-mmhf-85c7
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
NVD 8.8

Gitea 1.25.5 caches a branch-specific write-permission result across multiple refs in one pre-receive hook session, allowing a per-branch maintainer-edit grant to be reused for other refs and escalate to full repository write access.

Record
CVE-2026-27775
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
OSV 8.8

Gitea pre-receive hook permission cache allows full repository write access

Gitea 1.25.5 caches a branch-specific write-permission result across multiple refs in one pre-receive hook session, allowing a per-branch maintainer-edit grant to be reused for other refs and escalate to full repository write access.

Record
CVE-2026-27775
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
OSVGHSA-649p-mmhf-85c7 8.8

Gitea: Cached Per-Branch Permission Check in Pre-Receive Hook Allows Full Repository Write

Vulnerability Header

| Field | Value | | ------------------- | ----------------------------------------------------------------------------------- | | Vulnerability Title | Cached Per-Branch Permission Check in Pre-Receive Hook Allows Full Repository Write | | Severity Rating | High | | Bug Category | Authorization Bypass | | Location | routers/private/hook_pre_receive.go:55-64, CanWriteCode() | | Affected Versions | 1.25.5 |

Executive Summary

The pre-receive hook in Gitea evaluates the CanMaintainerWriteToBranch permission only once per git push session and caches the result for all subsequent refs in the same batch. An attacker who has a legitimate per-branch write grant (e.g., via an open pull request with "Allow edits from maintainers" enabled) can batch-push that branch together with any other ref. The cached true from the first ref is reused for all following refs, allowing the attacker to overwrite protected branches (including main), create arbitrary new branches, and push tags. This effectively escalates a single-branch maintainer-edit grant into full repository write access.

Root Cause Analysis

Technical Description

When processing a multi-ref git push, the HookPreReceive handler at hook_pre_receive.go:107 iterates over all incoming refs. For each branch ref, preReceiveBranch (:140) updates ctx.branchName to the current branch (:142) and then calls AssertCanWriteCode() (:144).

CanWriteCode() (:55-64) checks whether the user can write to the repository. On the first call, it evaluates issues_model.CanMaintainerWriteToBranch(ctx, userPerm, ctx.branchName, user) and stores the result in a boolean flag (canWriteCode) with a guard (checkedCanWriteCode). On all subsequent calls within the same batch, it returns the cached boolean without re-evaluating against the now-different ctx.branchName.

This means the permission check is branch-specific in its inputs but session-scoped in its caching — a classic check-vs-use divergence.

A second contributing factor is the AGit-flow relaxation at routers/web/repo/githttp.go:190-192 (and routers/private/serv.go:337-338), which downgrades the outer receive-pack access gate from Write to Read when git.DefaultFeatures().SupportProcReceive is true (git ≥ 2.29). This allows a user with only Read access on a repository to initiate a receive-pack session, deferring all authorization to the pre-receive hook — which contains the caching bug described above.

First Faulty Condition

| File | routers/private/hook_pre_receive.go | | --------- | ------------------------------------- | | Line | 55-64 | | Condition | CanWriteCode() evaluates the branch-specific CanMaintainerWriteToBranch check only on the first invocation and caches the result, reusing it for all subsequent refs in the batch regardless of which branch they target. |

Trace Analysis

The following is the path from the attacker's git push to the authorization fault:

  1. POST /{owner}/{repo}.git/git-receive-pack → routers/web/repo/githttp.go:437 (ServiceReceivePack) → httpBase() (:60)

    • Access gate is downgraded from Write to Read at :190-192 due to AGit-flow support.

  2. git receive-pack invokes the pre-receive hook → cmd/hook.go:184 (runHookPreReceive) → modules/private/hook.go:96 (HookPreReceive) → internal API → routers/private/hook_pre_receive.go:107 (HookPreReceive)

  3. Loop at :117 iterates over all refs in the batch. For each branch ref, preReceiveBranch (:140) sets ctx.branchName at…

Record
GHSA-649p-mmhf-85c7
CVSS 3.1
8.8 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-863
Updated
2026-11-02
OSVGO-2026-6043 No score

Gitea: Cached Per-Branch Permission Check in Pre-Receive Hook Allows Full Repository Write in code.gitea.io/gitea

Gitea: Cached Per-Branch Permission Check in Pre-Receive Hook Allows Full Repository Write in code.gitea.io/gitea

Record
GO-2026-6043
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
code.gitea.io/gitea
Go
 before 1.26.3
1.26.3
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-27775 is a high vulnerability (CVSS 8.8) in Gitea Open Source Git Server, published July 3, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.91%, the 60th percentile. Fixed in code.gitea.io/gitea 1.26.3.

References

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